Method for scanning image information

ABSTRACT

A method for scanning and generating image information includes generating a radiation beam and scanning an image field containing variable image information. Optical variations are detected in the image field, with electro-optical detection means to produce electrical control signals. The electrical control or detection signals are compared with information obtained from recordings in a memory. When an operable match is effected between select of the electrical detection signals and the information recorded in the memory, a coded electrical control signal is generated.

RELATED APPLICATIONS

This is a continuation of application Ser. No. 906,969 filed Sept. 15,1986, which is a continuation of application Ser. No. 723,183 filed Apr.15, 1985, now U.S. Pat. No. 4,660,086, which is a continuation ofapplication Ser. No. 394,946 filed Jul. 2, 1983, now U.S. Pat. No.4,511,918, which is a division of application Ser. No. 13,608 filed Feb.16, 1979, now U.S. Pat. No. 4,338,626, which is a division ofapplication Ser. No. 778,331 filed Mar. 16, 1977, now U.S. Pat. No.4,148,061, which is a continuation of application Ser. No. 254,710 filedMay 18, 1972, now U.S. Pat. No. 4,118,730, which is acontinuation-in-part of application Ser. No. 267,377 filed Mar. 11,1963, which is a continuation-in-part of application Ser. No. 626,211filed Dec. 4, 1956, now U.S. Pat. No. 3,081,379, and acontinuation-in-part of application Ser. No. 477,467 filed Dec. 24,1954, now abandoned.

BACKGROUND OF THE INVENTION

It is known in the art to record a series of picture signals on a movingmagnetic tape and subsequently reproduce the picture signals atessentially the same rate of recording to create a motion picture on avideo or television screen for visual observation. My patent applicationSer. No. 688,348, now abandoned, describes means for recording a videosignal of a single frame or screen sweep of the video scanning beam of acamera or flying spot scanner. The video signal may be reproducedthereafter and used to provide a still image picture on a video monitorscreen.

In U.S. Pat. No. 2,494,441, a method and an apparatus are disclosed forobtaining the average or mean dimensions of small particles by countingpulses generated in scanning a large number of small particles In thisparticular disclosure, it is necessary to mathematically calculate theaverage or mean particle size and possibly the area covered by theparticles by using mathematical formulas. However, it is not possible tospecifically pick out a particular particle and measure its size or areadirectly by using this prior art method and apparatus.

In U.S. Pat. No. 2,731,202, an apparatus is provided for counting thenumber of particles appearing in a field of view against a backgroundcontrasting in appearance with the particles. In this particular priorart structure, a beam is impinged on the viewing field. Whenever thereis a change in the beam intensity, an electrical pulse is produced andcounted. That is, this prior art method and apparatus merely provides asimple counting technique. There is absolutely no disclosure fordigitizing the image on the field of view to provide its location or thespecific dimensions thereof.

PURPOSE OF THE INVENTION

It is a primary object of this invention to provide a new and improvedautomatic scanning and inspection apparatus.

Another object is to provide an automatic image field scanning apparatuswhich is capable of automatically determining various characteristics ofthe field being scanned or any predetermined portion thereof.

Another object is to provide an automatic inspection apparatus employingone or more electron beams which apparatus is highly versatile and maybe used to perform a plurality of different scanning and inspectionfunctions without major modification to said apparatus.

A further object is to provide an automatic inspection apparatusincluding beam scanning means for analyzing an image or field with saidapparatus capable of providing the results of scanning directly in codedform which may be used by a computer.

Another object is to provide an automatic inspection apparatus forautomatically comparing or measuring a plurality of different dimensionsin an image field in a substantially shorter time interval than possibleby conventional inspection means.

Another object is to provide an improved means for electricallycontrolling and selecting portions of an image field being inspected.

A still further object is to provide an improved electro-opticalcomparator means employing beam scanning which does not require maskingan image field for effecting selective area scanning.

Another object is to provide an automatic inspection apparatus employingbeam scanning to determine dimensions and other characteristics ofarticles of manufacture, whereby both the work and the beam scanningmeans may be positionable by numerically controlled manipulators topresent predetermined portions of the articles to be inspected in thefield of the beam scanning means.

Another object is to provide automatic inspection beam scanning meansfor scanning and inspecting a plurality of different image fields whichmay comprise different areas of a workpiece.

Still another object is to provide means whereby a video picture signalmay be used to effect automatic quality control by the investigation ofpart of said signal.

Another object is to provide a means for effecting automatic measurementand quality control functions using two video picture signals. One is astandard signal of known characteristic and the other is a sample ortest signal whereby all or parts of said signals are investigated andcompared by their simultaneous reproduction from a magnetic recordingmedium on which they are recorded in a predetermined relative position.

Another object is to provide automatic means for reproducing a specificor predetermined part or parts of a video picture signal for computing,measurement or control purposes.

Another object is to provide automatic means for reproducing that partof a video signal derived during the scanning of a specific area of atotal image field without the need to control the scanning beam of avideo scanning device.

Another object is to provide means for operating on video picturesignals and for modifying or changing specific portions of said signalswhereby the altered picture signal may be used to produce a video imageor still picture of modified image characteristics.

Another object is to provide a recording arrangement including analogsignals with digital pulse code signals recorded adjacent thereto foridentifying portions of said signals.

Another object is to provide automatic scanning and control means foreffecting measurement or inspection of an article of manufacture on aproduction line for determining the dimensional or other physicalcharacteristics thereof.

Another object is to provide new and improved apparatus which may beused to effect various inspection, control and digitizing functions.

Another object is to provide automatic apparatus for measuring an objector surface including means for selectively measuring predetermined partsof said object and for providing information in code form resulting fromsaid measurement which code may be utilized by a digital computer.

SUMMARY OF THE INVENTION

As described herein, an apparatus and a method are provided fordigitizing an image field. Code signals such as binary digital signalsare generated when the image field is scanned. The code signals indicateinformation such as location of a line, the border of an object, thedistance between lines or borders, and areas. It would be possible toindicate information related to volumes when appropriate mechanism isprovided to scan in all directions.

In one embodiment of this invention, a beam scanning apparatus includesan electron beam which may be moved relative to a workpiece or imagefield to provide information or a picture field from a code signal whichhas been generated within the beam scanning apparatus. The apparatusfurther includes means for analyzing the code signal to determinecertain characteristics of the image field such as the presence orabsence of images or image portions such as components of an assembly,flaws, or other objects in the field, and the location and/or dimensionthereof.

The apparatus of this invention is applicable for the inspection ofarticles of manufacture. In addition, the apparatus may be used toautomatically analyze a field such as a drawing, photograph, map orelectronic picture as found on an oscilloscope. The analysis provides adetermination of the degree of certain characteristics of the field suchas light or dark areas which are indicative of certain known conditions.Such characteristics are obtainable in code form in one aspect of theinvention and are thus capable of being analyzed by a computer or otherdevice. In another form of the invention, apparatus is presented forautomatically analyzing a changing condition in an image field.

In another specific embodiment, the digitizing can be effected eitherautomatically by a flying spot scanner or by a cathode ray tube or bymanual techniques which currently use a photoelectric cell or some otherform of sensing device. Therefore, the digitizing may be accomplishedeither in constant speed or variable speed. That is, it can be doneeither by timing of a constant speed scanner or in proportion to thedegree of movement of an allied digital converter such as a wheel havingcodes associated therewith.

DEFINITION OF TERMS

Components and known circuits provided herein bear the following generalalphabetical notations in the various drawings. Unless otherwise noted,the circuits and components referred to herein and illustrated in blocknotation are standard circuits which are known in the art. Generaltitles, notations or terms such as "multi-circuit timer or controller","computer", "computing circuit", "recorder and/or computer", "signalanalyzer", "analog/digital converter", "clipper", "alarm", "storagetube", and "binary adder", are well known components and performspecific functions known in the prior art. The various componentsreferred to, while they perform their normal functions, have beencombined together in a new and unobvious way to effectuate a new andunobvious result not known in the prior art before the effective filingdate of the present application. Such prior art patents as U.S. Pat.Nos. 2,494,441; 2,731,202; 2,749,034; 3,081,379; 3,098,119; 3,239,602;3,539,715; 2,429,228; 2,726,038; 2,754,059; 2,735,082; 3,146,343;3,027,082; 2,979,568; 2,536,506; 2,615,306; and 2,729,771 are exemplaryof the manner in which such terminology is acceptable in the prior artto fully disclose the inventions claimed therein. As shown in theseprior art patents, all of the terminology referred to in the instantcase is clearly known in the prior art and thereby provides the skilledartisan sufficient disclosure to effectuate the invention of the presentdisclosure. Where a hyphen (-) follows the letter, it is assumed that amultiplicity of the devices or circuits are provided in the disclosure.

A- Amplifier, such as a reproduction amplifier for amplifying signalsreproduced by an associated magnetic reproduction transducer or pickuphead PU.

RA- Recording amplifier, used to record pulse or video picture signalson a magnetic recording member.

AN- A logical AND switching circuit which will produce an output signalwhen, and only when, signals are present at all inputs to said circuit.

CL- A vacuum tube or semi-conductor clipping circuit, preferably a videoclipper operating at a desired clipping level.

CM,CM'- A Schmitt cathode coupled multi-vibrator circuit, whichcomprises a cathode coupled multivibrator with an associated signalinverter at the output of the multivibrator. This circuit will produce apulse output when the leading edge of an elongated pulse appears at saidcircuit and a second pulse output when the trailing edge of said pulsereaches said circuit.

D- Delay line or time delay relay of required time constant. If a signalsuch as a video picture signal is to be delayed, D signifies a delayline.

IF,IFP- A scanning image field where video beam scanning is employed forinspection.

N- A normally closed, monostable switch or logical NOT switching circuitwhich will open and break a circuit when a signal is present at itsswitching input. It may be a vacuum tube, semi-conductor orelectro-mechanical device or any other logical circuits or gates.

OR- A logical OR switching circuit adapted to pass a signal from any ofa multiple of inputs over a single output circuit.

FF- A Flip-flop switch, electro-mechanical, vacuum tube orsemi-conductor circuit. A bi-stable switch adapted to: (a) switch aninput signal from one of two input circuits to one of two outputcircuits, (b) switch a signal from a single input circuit over one oftwo outputs depending on the described application. The flip-flop switchmay have two or three switching inputs depending on the application, acomplement input C which, when energized, switches a single input fromone output to the other and/or two inputs, each of which, whenenergized, switches the flip-flop to its respective output.

PB- A picture signal, preferably derived from beam scanning a fixedimage field IF. The signal may be amplitude modulated or frequencymodulated and may be the output of a conventional television scanningcamera, flying spot scanner or the like. It may be a continuous signalor may consist of a multitude of short pulses depending on the type ofscanning and signal formation employed.

The PB signal may also be derived from the output of a fixed photomultiplier tube with the image or object being scanned, being moved toprovide variations in said signal. For some applications, the PB signalmay be any analog signal derived from scanning, an analog or digitalcomputer or other computing device.

PC- Pulse code number. This may be any type of code (binary digit,decimal, etc.) recorded either longitudinally along a single channel ofa magnetic recording member or recorded laterally along a single channelof a magnetic recording member or laterally along a fixed path or lineacross multiple channels of said recording member, there being codepositions where said code line crosses each recording channel whicheither (a) contains or does not contain a pulse recording or (b)contains a positive pulse recording or a negative pulse recordingdepending on the design of the digital computing or switching apparatusto which the reproduced code is transmitted. If recorded along a lateralline of the recording member, the code PC may be reproduced at aspecific point in the reproduction of one or more picture or analogsignals adjacent thereto and may be used to effect a specific switchingaction when reproduced to affect a specific section or length of theassociated picture signal(s).

SW-A, limit switch.

SC,CS-A signal or signals preferably recorded in positions on a magneticrecording member to be reproduced simultaneously with a specific sectionof another picture or analog signal and used for gating or controlpurposes.

ST- refers to a video storage tube or storage device having a writinginput WI for recording a picture signal on the storage element of saidtube and an output RI, which, when a second input R2 is pulsed orenergized, passes a picture signal derived from the scanning of the readbeam of said tube.

CL- refers to a clipping circuit adjusted to clip at a specific clippinglevel. A diode, triode or other clipper such as used in video clipping.

IF, IFP- refers to an image or object field being scanned to produce apicture signal. The field in the optical system of a conventional orspecial television scanning camera. The field may also be the screen ofan optical comparator or projection microscope having a video scanningcamera or flying spot scanner focused and positioned relative thereto ina predetermined manner. The image or images in said field may be anyoptical or radiation phenomenon which provides an area or areas thereinof different radiation or light characteristic relative to other areasso that, in scanning across said different areas, the resulting picturesignal will change sufficiently to permit a measurement or measurementsto be made by electrically noting said changes or differences. The fieldmay also comprise a map, photograph, X-ray image or pattern, etc.

All of the above terms indicating various components may beinterconnected to accomplish their desired results by the skilledartisan. The drawings discussed herein below along with the descriptionof the specific embodiments clearly give guidance to the skilled artisanto select and interconnect each of the prior art devices to perform thedesired operations and effectuate the new and unobvious results as setforth herein.

BRIEF DESCRIPTION OF DRAWINGS

The various electrical circuits used herein for performing the describedmeasurement, comparison and indicating functions are illustrated inblock diagram notation for the purposes of simplifying the descriptionsand drawings.

The following assumptions are also made regarding the circuitry tosimplify drawings and descriptions:

In the diagrams, where junctions are illustrated between two or morecircuits which are electrically connected at said junction with afurther single circuit, it is assumed that a logical OR circuit isemployed at said junction.

Where a single circuit extends from a junction to two or more circuits,it is assumed that either a single input, multi-output transformer isprovided at said junction or said output circuits are resistancebalanced permitting any input signal to travel over both of saidoutputs.

Wherever circuits which require a power source, such as switching orlogical circuits, gates, clipping circuits, multivibrators, servomotors, controls, amplifiers, transducers, are provided, it is assumedthat a source of the correct electrical power or potential is providedfor said circuits. Power is also assumed to be provided on the correctside of all gates and relays where needed.

Various automatic measurement and comparison scanning techniques areprovided herein whereby a picture signal, derived from photoelectric, orvideo scanning an image field or part of a field, is recorded on amagnetic recording member such as a magnetic tape along a predeterminedlength of said tape and in predetermined positions relative to othersignals used for gating and control. When reproduced together, saidother signals may be used to effect one or more predetermined functionsrelative to said picture signal.

The method of recording all signals in predetermined relative positionson a recording member and then reproducing and using said signals in oneor more manners described herein has a number of advantages includingthe provision of a record which may be rechecked, if necessary, orotherwise monitored. However, in the embodiments provided, it is notnecessary to record the video or picture signal on the recording memberif means are provided for presenting said picture signal in therespective measurement or control circuit at a predetermined time inrelation to said other signals. For many of the functions described,particularly those where it is only necessary to measure or compareimages, a picture signal may be passed directly from a video storagetube or other photoelectric scanning device to the reproductionamplifier through which the reproduced signal passes. However, functionssuch as record keeping may require that the picture signal be recorded;hence recording arrangements are illustrated.

In the various magnetic recording arrangements and apparatus providedherein, picture signals are shown recorded on a magnetic recordingmember which also has other signals recorded thereon in predeterminedpositional relationship to said picture signals. The recording member isillustrated as an elongated flexible magnetic tape or the developedsurface of a magnetic disc or drum. While not illustrated, it is assumedthat known means are provided for driving the tape or drum at constantspeed past magnetic reproduction apparatus when constant speed is arequisite for the desired measurement. For example, when an automatictiming circuit is utilized to effect a measurement between twopredetermined points in the picture signal, the timing device and thedrive for the tape must be synchronized to start at predetermined timesand operate at predetermined rates. If the magnetic recording member isdriven at a predetermined constant speed, and if the timing deviceoperates at a predetermined constant rate and is started at an instantdetermined by the time of reproduction of one or more signals on saidmagnetic recording member, then a particular reading or value of thetiming device may be converted to a lineal distance or a coordinate inthe field which was scanned to produce said picture signal.

The above objects and other advantages will appear in the followingdescription and appended claims, reference being made to theaccompanying drawings forming a part of the specification wherein likereference characters designate corresponding parts in the several views.

FIG. 1 illustrates a portion of a recording member and an arrangement ofpicture signals and control or gating signals provided thereon inpredetermined relative positions;

FIG. 1A illustrates a portion of a multi-track recording member havingplural picture signals recorded adjacent each other and associatedcontrol or gating signals tandemly aligned with said picture signals;

FIG. 1B illustrates a portion of a multi-track recording membercontaining both picture and code signals recorded on different tracksthereof and also illustrates in block diagram notation, gating andcomputing circuitry for utilizing reproductions of recordings;

FIG. 1B' is a circuit diagram showing details of part of the computingcircuitry of FIG. 1B;

FIG. 1C illustrates a portion of a recording member containing picturesignals and controls and circuitry provided in the output of thereproduction transducers which scan said recording member;

FIG. 2 illustrates a portion of a multi-track recording member havingsignals of predetermined duration or length recorded thereon inpredetermined positions relative to recorded picture signals forindicating, when reproduced simultaneously with said picture signals,dimensional ranges of the physical phenomenon or objects scanned togenerate said picture signals;

FIG. 3 illustrates a recording and reproduction arrangement wherebycontrol means are provided for blanking all but predetermined orparticular portions of one or more picture signals so that the remainingportion or portions of said picture signals may be analyzed withoutinterference from the other portions;

FIG. 4 illustrates a recording and reproduction arrangement foroperating on a picture or analog signal in a manner similar to thatillustrated in FIG. 3 to effect one or more dimensional measurements orcontrol functions;

FIG. 4' is a fragmentary view of a scanning field illustrating thephysical significance of certain of the signals recorded on therecording member of FIG. 4;

FIG. 4A illustrates a circuit applicable as a replacement for a portionof the circuit of FIG. 4;

FIG. 4B illustrates a digital code generator or clock applicable to thecircuitry of FIG. 4 to effect measurement functions;

FIG. 5 illustrates a recording arrangement with predetermined positionedsync and gating signals;

FIG. 6 illustrates the recording arrangement of FIG. 5 and circuitcomponents utilizing the signals provided thereon;

FIG. 7 illustrates a modified form of the recording arrangement andcircuit components of FIGS. 5 and 6;

FIG. 8 illustrates a recording arrangement and a reproduction circuitdiagram utilizable for effecting automatic dimensional measurement;

FIG. 8' illustrates a scanning field showing physical aspects of thesignals recorded in FIG. 8;

FIG. 9 illustrates a recording arrangement and reproduction circuitrytherefore applicable for measuring the various dimensions of distancesin an image field and providing said measurements as coded signals;

FIG. 10 illustrates a clipping level adjustment means applicable to partof the apparatus of FIG. 9;

FIG. 11 is a more detailed view of a portion of FIG. 10;

FIG. 12 is a more detailed view of a portion of FIG. 9;

FIG. 13 is a perspective view of a scanning station utilized to providesignals which are applicable to the recording and measurementarrangements illustrated in the other drawings;

FIG. 14 is a plan view of FIG. 13, which view also illustrates recordingand dimensional measuring components;

FIG. 15 is a schematic diagram showing a circuit employing a summingamplifier to generate pulse signals;

FIG. 16 is an isometric view of an inspection station employing meansfor prepositioning both a scanning apparatus and a workpiece;

FIG. 17 is a diagram of control apparatus for the apparatus of FIG. 16and also illustrates means for recording and analyzing the resultsobtained by scanning;

FIG. 18 shows another control arrangement applicable to the apparatus ofFIG. 16;

FIG. 19 shows an automatic scanning system having a scanner which ispositionally controllable to continuously scan different image fieldsand includes means for indicating when changes occur in said imagefield; and

FIG. 20 shows a scanning arrangement employing a plurality of differentscanners each adapted to scan a different image field or phenomenon.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The video information signals recorded on the magnetic recording mediumsillustrated in FIGS. 1 through 9 may be derived by using a televisionscanning system and the components as shown, for example, in FIG. 14.

A number of recording, reproduction, scanning and comparisonmeasurement, counting, control and computing functions are describedherein. Additionally, an apparatus utilizes a video picture signalderived by electron beam or flying spot scanning of an object or imagefield or a video storage tube surface.

For most of the above functions, the picture signal or signals arerecorded in a fixed or predetermined position on a magnetic recordingmember such as a magnetic tape or drum and relative to one or morecontrol and/or gating signals which will be denoted by the notations SCor CS. These control signals are specified as constant amplitude pulsesignals of a short or predetermined duration. However, they may also beof variable amplitude and/or frequency depending upon the type ofoperation or function controlled thereby.

One technique comprises the scanning of an image or optical field suchas a predetermined area of a surface of a workpiece or assembly, or animage field in which a portion thereof contains an object or pluralityof objects or areas having an optical characteristic which isdiscernible from the characteristic of the surrounding field orbackground. For example, the image may have different color or lightcharacteristics which investigation involves the analyzing of a lengthor lengths of the video picture signal produced when the image oroptical field is scanned by a video camera or flying spot scanner.

If automatic scanning or comparison measurement using a change in aportion of a video signal is to be employed for measurement or analysisof the optical characteristics of the field from which the signal wasderived, then there is a requisite for such measurement. If it is to bemeaningful, the area, object or other phenomenon in the field beingscanned must be at a known distance from the scanning camera, opticalsystem or the flying spot scanner so that its scanned area will be to apredetermined scale in the image field.

The attitude of the object or plane being scanned must also be fixed orpredetermined relative to the axis of the video scanning device. Aplane, point or area of the object should also be known or referenced inposition in the field being scanned. The requirement for any automaticmeasurement is that a base or benchmark be established. The measurementor comparison is effected in this invention by a scanning means which isutilized to indicate the existence of an area, line or plane in thefield being scanned. Therefore, the above mentioned scale, alignment andpositional requisites must exist to a predetermined degree or tolerancein order to attain a predetermined degree of precision in themeasurement. It is thus assumed that where dimensional measurement,comparative image analysis or other investigations involving thescanning and analysis of a specific area or areas of the total field aredesired, the object, surface, or area being scanned is prepositioned,aligned and provided at a predetermined scale in the scanning field. Forthe automatic and rapid investigation of multiple articles or assembliesby this method, a jig, fixture, platform or other form of prepositioningstops may be provided to preposition the articles at a fixed distanceand attitude relative to the video scanning device. Preferably at leastone surface area or point of said article is at a predetermined point,plane or position in space.

The following physical conditions may be measured, indicated or comparedby means of the automatic measurement apparatus provided herein:

(1) Indication of the position of a line, point, border of a specifiedarea, or a specified area in a given image field. This may be providedas a coded signal or series of coded signals which are indicative ofsaid position or positions from a base point or line in the field or ata specified distance from the field.

(2) Determination if the point, line or area is positioned in apredetermined area or position in said field, and if not within limits,how far the image falls or is positioned away from the predeterminedposition.

(3) Determination if the point, line or area in the field being scannedfalls within a specified distance or region such as a tolerance range,one or either side of a specified position.

(4) Determination in which of several specified regions in an imagefield being scanned, each of which encompasses a different area eitheror both sides of a specified position or area in said field, a point,line or area falls. This function pertains to automatic sortingoperations.

(5) Determination if a predetermined image exists or does not exist in aspecified area of an image field. If so, determination also as to howmuch or to what extent the area falls in the specified area. Thisfunction pertains to inspection functions to determine if imageconditions exist such as surface defects, markings, assemblies, orinternal defects thereby X-rays are used to provide the image.

(6) The measurement of the dimension or dimensions of an image in afield by scanning part of said image at a constant scanning rate andtiming the scanning from one point in its travel across an image toanother.

An erasible recording member, generally designated 10, may be a magnetictape or the developed surface of a magnetic recording drum, showingsignal arrangements thereon which are basic to this invention. Thelateral and longitudinal dimensions of the signal recording channels orareas illustrated are not necessarily to scale or of equal scale andmerely illustrate the relative positions of the various signals on therecording member so that their coacting functions may be described.

In all the figures illustrating relative signal areas, one of severalrecording and reproduction systems may be provided whereby, while thetotal recording pattern may vary, the positions of the various coactingrecordings relative to each other will essentially remain the same topermit the same functions to be accomplished in one recording system asin the other. For example, if the magnetic recording tape or drum ismoved relative to one or more recording heads which remain stationary,then a series of parallel areas or tracks will be traced by the heads asillustrated in FIG. 1. However, if the recording heads are driven in arotary path and sweep across the recording medium as the latter moves ina fixed path relative to the rotational axis of said heads, then aseries of recording areas oblique to the longitudinal axis of the tapewill be traced thereon by the heads. The end of each oblique recordingchannel area or head sweep will be continued further along the tape asthe beginning of a new oblique trace. Thus, any video and control signalrecording arrangements illustrated in one figure as provided onrecording areas or channels which extend parallel to the longitudinalaxis of the recording medium or tape, may also be provided on theoblique, repeating recording areas of others of said drawings such asFIG. 5 if the same relative positioning of said adjacent signals ismaintained in the oblique recording.

More specifically, referring to FIG. 1, a sync signal S1 and a picturesignal PB1 are recorded on multiple side by side recording areas of therecording member 10. Each of the signals S1 and PB1 is recorded on aseparate channel thereof in a predetermined position with respect to theother channels. The sync signal S1 is recorded on a first channel ortrack C1 which indicates and may have been used to effect the precisepositioning of the picture signal PB1. The picture signal PB1 is derivedfrom beam scanning of the image field such as a video signal. The fieldmay or may not contain the frame blanking signal component. The picturesignal PB1 is shown recorded on a second channel C2. The picture signalPB1 may be a recording of the signal output of a video scanning devicesuch as a video camera employing a vidicon, iconoscope or other scanningtube or a flying spot scanner.

If it is desired to provide a visual display of the PB1 signal at sometime after its reproduction from 10, the duration and character of thePB1 signal is preferably such that it may be used when reproducedtherefrom to modulate the write beam of a video picture or storage tube.In my copending application, Ser. No 688,348 filed in 1957, the outputsignal of a video camera or storage tube equivalent to the signalderived from the video camera scanning read-beam is recorded during asingle frame or screen sweep either in an image storage tube or on amoving recording member. Thereafter, the signal is reproduced at videofrequency and used to modulate the picture generating write-beam of avideo monitor-screen.

The PB1 signal of FIG. 1, if intended to later reproduce a visual imageon a monitor screen, is thus preferably an image, single frame videopicture signal. The beginning of the picture signal is positionedadjacent to or in predetermined relation to sync signal S1 such thatsync signal S1 may be used to control the reproduction of the picturesignal PB1. For faster scanning, the start of the picture signal may bedefined as a predetermined point occurring at or after the framevertical sync signal appears when the socalled read beam starts itsframe sweep.

In the inter-laced scanning system, each complete sweep of the camerascanning beam is referred to as a "field" sweep and two of such imagefields make up an image "frame". As stated, the PB1 signal preferablyhas provided therewith the associated frame blanking signal so that itmay be used to effect the production of a video image, if necessary, fordisplay purposes. For specific computing or operational functions, itmay be desirable to merely compare part of the PB1 signal with anothersignal whereby only part of a single frame signal need necessarily berecorded and the blanking component of said signal may be eliminated.The sync signal S1 may be used as a trigger signal recorded on apredetermined position of member 10 and used thereafter to trigger orotherwise effect the recording of the PB1 signal on a predeterminedrecording area or channel of member 10. If the PB1 signal is recorded atrandom on member 10, sync signal S1 may be used as an indicator of theposition of the PB1 signal and of another signal or signals alsorecorded thereon.

A third channel or band recording area C3 parallel to bands C1 and C2,contains the necessary video horizontal line sync signals HS. The syncsignals HS are recorded in a predetermined position relative to PB1 forthe correct horizontal deflection and synchronization of the picture andblanking signal PB1 to effect the production of a video image.

A fourth channel C4 runs parallel to the other channels and contains theassociated vertical synchronization signal VS1 for vertical line andframe synchronization of the picture signal PB1. The latter two signalsHS and VS1 are optionally provided in the event that it is desired toreproduce the PB1 signal as a picture on a video screen for monitoringor other purposes.

One or more additional recording channels or areas C5, C6, C7, C8, C9and C10 preferably extend in a direction parallel to and are adjacent tothose channels described hereinabove. The channels C1, C2, etc. containone or more operational gating or command signals CS1, CS2, etc. whichmay be either pulse or analog signals. The command signals CS1, CS2,etc. are preferably provided in predetermined fixed positions relativeto the picture signal PB1 located on channel C2 to be reproducedtherewith and are used to modify, gate or operatively coact with thevideo signal PB1. While the various control signal or signals CS1, CS2,etc. may be recorded at any time on the recording medium 10, if theirprecise position relative to the video signals is an important factor,their recordation may be triggered by the synchronizing signal S1 whichindicates the position of the video signals. If precisely relative tosync signal S1, the CS signals will also be precisely positionedrelative to the video signal or signals and may be used to effect one ormore operative or measurement functions on or in coaction with the PB1signal.

The command signal or signals CS1, CS2, etc. may be provided in one ormore forms. A single pulse, such as CS1, may be recorded on a singlechannel of member 10 and positioned adjacent a specific length of thevideo signal or signals. When reproduced therefrom as said member 10moves relative to respective reproduction heads, the pulse signal CS1may be used, for example, to gate an adjacent similar length of thevideo signal over an output circuit for scanning, modifying, measuring,clipping or otherwise operating on or cooperating with said videosignal. Thus, the position as well as the length of the pulse signal CS1will determine what section and length of the video signal will be gatedor otherwise operated on. The other operations controlled by CS1 mayinclude magnetic erasure, attenuation, amplification or othermodifications to said video signal adjacent or behind said pulse signalon channel C5.

While the CS1 signal may be a constant amplitude signal or pulse of anydesired length, it may also be an analog signal of varying amplitudeand/or frequency which is utilized to perform a more complex function ona particular section or sections of the video signal.

A series of other command or control signals CS2, CS4, CS5 and CSC arelaterally aligned bit pulses. Each pulse is on a different channel andcapable of being simultaneously reproduced therefrom by respectivemagnetic heads which are preferably aligned and scan a separate track orarea referred to by the notations C6 to C10. The series of pulses may bein the arrangement of a digital code PC, such as a binary code, and maybe used to effect circuit selection, computing and/or switchingfunctions. Circuit selection functions may be operative to (a) affect aspecific section or length of the video signal, (b) select a specificsection or sections of said video signal for reproduction, (c) adjust orotherwise affect one or more electrical components or circuits in theoutput of the reproduction head or heads of the video signal or (d)select one of a multiple number of circuits through which part or partsof said video signal may be gated for measurement, inspection orscanning functions to be performed thereon.

While the CS2, CS3, CS4, etc. signals illustrated in FIG. 1 are shownaligned laterally across the medium or tape 10 for simultaneousreproduction by aligned magnetic heads, they may be provided in anypositional arrangement which will be determined by the positioning ofthe magnetic reproduction heads and the required function of saidsignals. The signals CS2, etc. may be formed as a pulse chain byproviding the necessary delay lines or elements in the output circuitsof the respective reproduction heads. Furthermore, a pulse chain forcomputing and (or) control or switching purposes may be provided on asingle track adjacent the video signal in the form of the appropriatetandem pulse signals or multiple pulse chains may be provided thereon.Preferably, the pulse chains are sufficiently in advance of the videosignal or a section of the video signal which it is to affect or gate,to permit a switching, computing or shaft positioning action to takeplace prior to the reproduction of the desired section of said videosignal. The position of said recorded signal or signals on member 10,will also be a function of the relative positions of the variousreproduction heads.

A code or bit number PC' is shown as a series of tandem pulses on thechannel C10 and having the binary value 1110101. The code PC' isprovided as a series recording to illustrate that such a means ofrecording numerical information may be used with an adjacent analog orpicture signal to be reproduced prior to, during or after thereproduction of said picture signal for effecting computing and/orcontrol operations to be performed on or in coaction with thereproduction of said picture or analog signal, or in relation to atleast part of said signal. If the series code PC' is utilized forcomputing and control purposes adjacent a picture signal PB, then stillanother channel (not shown) is preferably provided with a series ofequi-spaced, equiduration pulses recorded thereon at preferably theinterval of the pulses of PC' to act as a clock when reproducedsimultaneously therefrom thus simplifying digital operations in aswitching circuit or computer using said pulse code.

The recording of the picture signal PB and the associated sync signalson the magnetic member 10 has many advantages such as the provision of apermanent record which may be referred to at any time or reproduced byselective means whenever needed and visually monitored by modulation ofthe picture generating beam of a monitor screen device. However, said PBsignal need not be recorded provided that said signal may be otherwisegenerated in a measuring or computing circuit at a predetermined instantrelative to the generation of said other illustrated signals. It isfurther noted that multiple, tandemly recorded picture signals may beprovided on one or more of the channels of the recording member 10 ofFIG. 1 with the associated gating and/or code signals for record keepingand computing purposes.

FIG. 2 shows a second picture signal PB2 which may be selectivelyreproduced by use of a predetermining counter receiving the positionindicating signals on channel C1. Upon reaching a preset count, signalPB2 closes a switch between the reproduction transducer reproducing fromthe channels C2 to C4 when that section of the tape 10 containing theselected picture signal PB is adjacent the reproduction transducer.

The parallel code PC may be placed prior to, or after the reproductionof the associated picture or analog signal PB. If recorded prior tosignal PB, said code PC may effect a specific switching or adjustingaction. During the reproduction of a particular segment of the PBsignal, said PC signal may gate or effect an action on a specific lengthof said PB recording. If placed on member 10 in a position to bereproduced after the reproduction of the PB signal, the PC signal may beused for effecting a computation obtainable in digital form from otheroperation on the associated picture signal or a part or parts of saidsignal.

It is noted that the recording arrangement of FIG. 1 is subject tomodification depending on the switching and logical circuitryoperatively connected to the output of the transducing apparatus formeasuring and performing operations on the associated picture signal,viz:

I. The laterally aligned pulse code PC which, in FIG. 1, is provided forreproduction prior to the reproduction of a section or length of theassociated picture signal, to perform a switching, gating, computing orother functions may be recorded adjacent a particular point in thepicture signal PB for effecting a specific switching function or otheraction on or simultaneously occurring with a predetermined length ofsaid picture signal. One such function described hereinbelow providessaid code or signals in relay storage to be subtracted from or added toa numerical code derived from operating on a specific length of thepicture signal.

II. The illustrated pulse code PC which is shown recorded for a shortduration in FIG. 1, may be recorded on a longer section of member 10 andmay vary in length from a short pulse such as the shortest signal whichmay be recorded thereon, to the entire length of the picture signal PB.When the code PC is reproduced, the output circuits of the associatedreproduction heads will each either have a signal or no signal presentduring the period a particular code is reproduced whereby said multiplecircuits define a code pattern or bit number at any instant. If it isdesired to have this code present for a specific period of time whichmay represent such phenomenon as a tolerance range, it will be necessaryto record the signals reproduced to provide the PC code recorded onmember 10, for a time during which said predetermined condition orchange in said picture signal will occur. If said code PC is thusrecorded as one or more pulse recordings of prolonged and predeterminedduration or length next to a predetermined section of the picture signalwhereby said position is such that it will be known that said prolongedcode PC will exist in output circuitry for a time duration during whicha particular change in amplitude or frequency in the picture signal willoccur, then said code will be known to exist when said change occurs andwill be available for reproduction therewith for effecting switching orcontrol functions, some of which will be described.

III. A series of parallel code recordings PC may exist in tandem arrayalong member 10 in a manner whereby, when the end of one code stops, thenext begins on the next length of said tape. Thus every point or lengthof member 10 will have an associated parallel code, such as a binarydigital code, which will identify said point or length. If a signal orsignals such as an analog signal, video picture signal, or other signalor signals are recorded adjacent said chain of said pulse codesrecordings PC, the output circuits of the transducers reproducing saidcodes will be energized with a predetermined code array during thereproduction of a particular length of an adjacent signal whichcondition will be indicative of the position of the part of saidadjacent signal being reproduced at the time the code is reproduced.

If the PC signals are of a binary or other numerically progressingorder, whereby each code array occupies the same length of member 10 asthe others and each successive code array is of a numericallyprogressing order (i.e. a binary digital signal order whereby one signalarray is a unitary increase over the prior recorded code or the sameincrement as each successive number from the prior number), then therecording member 10 may be used essentially as a digitizer. If driven atconstant speed, recording member 10 may be used as a digital timer orclock whereby a code, existing in the output circuits of the transducersreproducing said recorded code tracks, will be indicative of the timelapse from the start of travel of said member 10 provided that the coderecorded at the start of the cycle is known. The member 10 may be aclosed loop tape or drum running continuously and at constant speed. Itmay be used as a digital clock by providing a normally open electronicswitch or gate in the output of each of the reproduction transducersreproducing from channels C6 to C10, the code recording channels, andpulsing all said gates simultaneously to effect their closure for abrief period of time at the start of the interval being measured and atthe end of said interval. The pulse code passed through said gates whenfirst closed may be held in relay storage and may be added to orsubtracted from the pulse code passed therethrough at the end of saidinterval. The result of subtracting the smaller of said two code numbersfrom the larger number will be indicative of the time lapse between thetwo provided that the speed of the recording medium is known and thelengths of the code arrays are also predetermined and similar. If thedrive shaft of the recording medium 10 is connected to an analogmechanism, then the recording medium and drive may be used as an analogto digital converter of much greater capacity and duration than theconventional coded disc converter.

FIG. 1A illustrates a recording arrangement of analog and digital orcoded pulse signals, which are functionally related to each other. Anelongated magnetic recording member 10 is provided having multiplerecording channels C1 to CN (where N is any desired number). The channelC1 has a series of pulse signals PSG recorded as a group or as trainsthereon comprising short pulse recordings positioned at equi-spacedintervals, which may be reproduced and transmitted to a binary counteror other device for identifying any specific section or length of member10 as a result of the nature of said particular code. When theequi-spaced, short pulse recordings PSG are reproduced and passed to apulse counter such as a decade counter, they will indicate any positionon said member 10 by the existing value of said counter.

The even numbered channels C2, C4, C6, etc. contain signal recordingsincluding one or more pulse codes PC such as digital codes, followed byone or more analog signals ASG1 which may be the aforementioned picturesignals PB derived by scanning a fixed path in a field. The odd numberedchannels C3, C5, C7, etc. may contain other information in pulse or codeform such as a signal, S1, S13, for indicating the position of the startof the associated analog signal such as ASG1-3. The signal S1-may alsobe positioned at any predetermined location along the respective channelfor switching the output of the reproduction transducer reproducing aparticular part or all of the associated analog signal. The said outputmay be switched thereby for example, from an input to a digital computermechanism adapted to receive the associated PC codes to the input of ananalog device for receiving the ASG signal reproduced thereafter. Theswitching signal on the odd channels may also be incorporated andpositioned on the even channels between said digital code signals andanalog signal such as the illustrated SWS- signals of FIG. 1A.

The analog recording or recordings ASG1-1, ASG1-2, ASG1-3, etc. may berecorded in one of several forms. Said signals may comprise picturesignals of different but related phenomena such as derived from thescanning of one or more surfaces of a work member from different angles,two or more signals derived from scanning a standard field and field tobe compared therewith, or the simultaneous output of one or more analogrecording devices or instruments which are all functioningsimultaneously to measure for example, simultaneously changing variablesof a process or test. The digital signals preceding each analog signalor signals on each recording channel may be used to preset one or moremeasuring circuits in a manner to be described, to select a particularlength of the analog signal for reproduction, or to gate said signal orpredetermined sections of said signal as indicated by said code signalover one or more of a multiple of circuits.

An application of the recording arrangement of FIG. 1A is in the fieldof machine tool or process control. For example, the analog signalrecordings ASG may have each been obtained from the output of a synchroor selsyn generator which is operatively coupled to the shaft of a motordriving a part of a machine.

The significance of providing a recording of the type illustrated inFIG. 1A whereby one or more command analog signals on one or morechannels of the recording member 10 are preceded by one or more pulsecodes PC' is that the pulse codes may be used for effecting broadcontrol of the tool driving motor whereas the analog signaltherefollowing may be used to effect a finer control ormicropositioning. Also, while the pulse code on a specific channel ofmember 10 may be used to effect a stepped or intermittent control of themotor driving the tool, the analog signal may be used to effectcontinuous control of the speed and position of said motor. Numerousmachine tool and materials handling applications exist where thecombined digital-analog recording means of FIG. 1A is applicable toadvantage.

The digital signals may also be used to preset measuring devices andperform other switching functions in coaction with the operationcontrolled by the analog signals, which functions are not convenientlyderived from said analog signal per se. Further, the digital codes PC'may be used to control the direction and speed to the motor driving therecording member 10 in a predetermined manner. For example, it may berequired in the cycle of operation of the device controlled by analogsignal associated therewith to repeat the control effected by a limitedduration analog signal. The digital or pulse code preceding the analogsignal may be used to preset a recycling timer or may be held in relaystorage and used to control the future motion of the tape or recordingmember 10 so that the an log signal associated therewith is repeatedthereafter or parts of said signal are repeated in a predeterminedmanner.

Pulse recordings S2' to S8' are provided on the even numbered channelsbetween the groups of serially recorded pulse bit codes PC' and theanalog or picture signals ASG-. The recordings SN' are preferablyseveral times the length of the pulses comprising the PC' recordings sothat they may be used to actuate a relay which is responsive only to thelonger signal. The relay is used to switch the output from therespective reproduction transducer from a digital control device to ananalog device or circuit prior to the appearance of the reproduced ASGsignal. It is noted that the odd numbered channels C3 to CN may containa parallel pulse code for effecting an operation at a specific point orpoints in the reproduction of one or more of the analog signals.

FIG. 1B shows multiple recordings on a magnetic recording tape or drum10 driven at constant speed past multiple magnetic reproduction headsPU. The heads PU-1 to PU-8 (heads PU-4 to PU-8 are shown in FIG. 1B)reproduce the signals recorded on the respective channels C1 to C8. Onchannel C1 there is recorded a sync signal, such as S1 of FIG. 1, forindicating the position of the start of a picture signal such as a videopicture signal PB recorded on channel C2. Signal PB may also be anyanalog signal on which a measurement or operation is to be made. Onchannel C3, one or more gating signals SCN are recorded for switching aselected length of lengths of the reproduced adjacent PB signal to oneor more measurement or clipping circuits.

The channels C4 to C8 contain multiple pulse recordings arranged in amultiple code or binary scale order such that the heads PU4 to PU8 will,at any particular instant while reproducing from said channels, beenergized in a specific code order. That is, at any instant the paralleloutputs of said transducers will be energized in a signal arrayequivalent to a code.

The code scale recorded in FIG. 1B is a so-called progressive code withthe number zero at the point X1 and the number 32 at X2. A so-callednatural binary code recording may also be used as may any code meanswhich will provide a different code or signal array during each unitlength or increment U in the tape or drum 10. On channel C8, the pulsesignals are equispaced and have a length of 2U or twice the unit length.If the reproduction heads PU1 to PU8 are aligned as shown laterallyacross the member 10, the code existing in their output circuits willdepend on which unit lengths of the recording member said heads arereproducing from at the particular instant. If the member 10 is a closedloop tape or drum and is driven at constant speed relative to said headsPU, then the recordings on channels C4 to C8 may be used for timing orclocking purposes or may measure the distance between any two points orchanges in the associated PB signal.

The time between any two instantaneous or short duration occurrences maybe determined automatically as a numerical or binary code by themechanism as shown in FIG. 1B. By applying the proper constant orconversion factor to the result, the distance between any two points inthe associated picture signal PB and/or the distance between any twopoints in the image field scanned to produce said signal may beobtained. The combination of the recording member 10, a constant speeddrive therefor, the reproduction apparatus and the illustrated circuitrymay be used for performing any automatic timing function in which arapid readout is desired in pulse code form of a time interval betweentwo pulses passed thereto. The time interval may be any two instances ina timing or measurement cycle of any event whereby means are provided ateach instance to produce a pulse of short duration. The apparatus ofFIG. 1B may also be used to provide a binary or other pulse code foreffecting computational or control functions at various instances in ameasurement cycle whereby each instance is characterized by anassociated pulse signal. The running code may also be recorded onadditional channels of member 10.

The output of each of the magnetic reproduction heads PU4 to PU8 ispassed to a respective reproduction amplifier A4 to A8 and thence to theinput of a respective normally open monostable gate or switch G4 to G8.The output of each gate is passed to a computer or computing mechanismCO, one form of which will be described and is illustrated in FIG. 1B'.Device CO may also be an automatic recorder. The outputs of thereproduction amplifiers A4 to A8 are only passed to computer CO when theswitching inputs to said gates G4 to G8 are energized.

Simultaneous energization of all gates G4 to G8 is effected to provide acode output indicative that the heads are reproducing from a particularunit length U of member 10 by passing a pulse to the input of a multipleoutput pulse transformer PT. Each output of pulse transformer PT isconnected to a switching input of one of the five normally openmonostable gates or switches G4 to G8. The gates G4 to G8 are electrontube or semi-conductor devices capable of switching in the megacyclerange. Thus any condition occurring in the signal PB during the intervaldefined by reproduction of the SC signal or signals may be indicated asa code. If the code occurring on channels C4 to C8 is of a numericallyprogressing order, then the distance or time between the appearance atthe input of pulse transformer PT of two pulses may be indicated bysubtracting one code so generated from the other.

If the recording member 10 of FIG. 1B having the code scale recordingsillustrated on channels C4 to CN is a closed loop magnetic tape, it maybe used as a component of an analog to digital converter of greaterversatility than the conventional coded disc type of converter. Assumethat the member 10 is driven by the conventional capstan-depressor driveand there is no slippage in the driving means. Then the shaft of thecapstan or a shaft coupled thereto may be digitized. That is, any degreeof rotation of said shaft may be indicated as a numerical code or numberby providing a pulse at the input to pulse transformer PT at any instantin the rotation of said shaft. Since the code reproduced from member 10will be a function of the rotation of the capstan shaft, a coded numbermay thus be obtained for any degree of rotation of said shaft.

An elongated flexible magnetic tape with the code recordings asillustrated in FIG. 1B offers a coding surface of considerably greaterlength than the conventional coded disc. As such, the code may extend asa greater numerical value than on the conventional disc convertersurface thus eliminating counting circuitry and providing a considerablyhigher numerical value in code form than on the surface of the disc.

If the recordings on channels C1 to C3 comprise multiple picture signalsor information in the form of bit recordings such as binary code, therecording of a progressing numerical code as in FIG. 1B on said adjacentchannels C4 to CN may be used for a number of purposes. Said code may beused for the selective reproduction of any specific adjacent recordingsuch as a bit number or a specific length of PB signal, or thereproduction of one of a multiple of said picture signals fortransmission to further control or computing apparatus. Said code rayalso be used to identify a particular section of said tape for recordinga selected signal or bit information. These functions may be effectedaccurately without the use of a counter counting drive shaft rotationsor short pulse recordings and has ar advantage over the lattertechniques in that each point in the length of member 10 is identifiedby an associated code, whereas counting means are subject to errors if apulse should be accidentally erased.

If the device of FIG. 1B is used as an automatic interval timer,recording member 10 is driven at constant speed. Then the computingcircuit CO includes means for computing the time lapse between twooccurrences by subtracting the code occurring at the reproduction headsat the start of the interval to be timed from the code appearing thereat the end of said interval. The difference will be proportional to theactual time it takes for said codes to pass said reproduction heads. Ameans for obtaining said difference automatically is illustrated in FIG.1B', which shows part of the circuit. If the code on channels C4 to CNis a binary code, subtraction may be effected by a method known ascomplement addition. That is, the complement of a number is formed in acomplementing circuit (CC) and added to the second number. The result isthe difference between the two numbers.

In FIG. 1B', the circuitry for effecting this operation is illustratedin part. The circuit comprises one single-input, dual-output bistableswitch or flip-flop FFN in the output of each gate GN. The switches FF8and FF7 are part of the chain of said switches and are each shown with acomplement input. When pulsed, the complement input switches the outputof said switch from the existing condition to the other of its switchingconditions. Said switches FFN preferably also have a reset input which,when pulsed, switches the input to the other of said two states in whichit has been placed or if in said reset state, maintains said resetcondition.

Assume that the reset condition of each flip-flop is the illustrated "O"or left hand output and that all flip-flops are in this condition priorto the appearance of the first point in the timed interval. Then anypulses of the coded number passed through the gates G4 to GN will passthrough said "O"outputs of said flip-flops. The "O" output of eachflip-flop is thus connected to a respective input of a first shiftregister SR1 which converts the parallel bit code passed through thegates G4 to GN to a series code which is passed to the complementingcircuit CC. From the complementing circuit CC, the complement of thenumber is passed to one input of a binary adder BA.

The second coded number is obtained at the end of said measuring cyclewhen a pulse appears at the input to the pulse transformer PT. Thissecond coded number is passed through the flip-flops FF4 to FF8 to asecond shift register SR2 from which it is passed as a series code tothe other input of the binary adder BA. The result, which is transmittedfrom the adder as a code, is the difference between the two numbers andis proportional to the time between the receipt of the two pulses at theinput of pulse transformer PT.

Switching of all flip-flops to their output conditions "1" is effectedby passing a reproduction of the first pulse passed to pulse transformerPT through a delay line or time delay relay D and then to the input of amulti-output pulse transformer PT'. Each output of pulse transformer PT'is connected to a respective complement input "C" of a respectiveflip-flop to switch said bi-stable switch to its other output condition.The next signals to pass through the flip-flops are thus passed over the"1" outputs to the shift register SR2.

The duration of the delay D will depend on the switching times of thegates GN and flip-flops FFN as well as the shortest time intervals to bemeasured. The pulses to pulse transformer PT, as will be describedhereinbelow, may be derived from such a phenomenon as a specified changein the associated recorded PB signal. The technique may be used tomeasure distances in the image field scanned to produce the picturesignal PB as described hereafter.

If the flip-flops and circuits CC, BA and SR2 are eliminated, theresulting outputs of shift register SR1 or of the gates GN may berecorded as indications of the coordinate positions of specified linesor areas in the field scanned to produce the picture signal PB. For thecircuit of FIG. 1B' to function, the code scale on channels C4 to C8will be a binary code.

The input to the pulse transformer PT of FIGS. 1B and 1B' may betransmitted from such circuit arrangements as the following:

(A) In FIG. 3, the output of the Schmitt circuit CM may be passed topulse transformer PT as shown in FIG. 1B to measure and present as a bitcode signal the length of the signal passed through the "not" circuit N.The output of either clipper CL1 or CL2 may also be passed to a Schmittcathode coupled multivibrator circuit, the output of which is connectedto the input of a pulse transformer, the alternate arrangement not beingshown. In one embodiment, the gating signals illustrated in FIG. 3 areprovided in predetermined positional relationship to the associatedpicture signal such that part of the picture signal which was producedduring the line scan of a predetermined portion of the image fieldcontains an area the width of which it is desired to measure. Theclipping circuit produces a signal output when the input is that part ofsaid picture signal produced during scanning said area. Consequently,the leading and trailing edges of said signal will cause said Schmittcircuit to produce short pulse outputs. The circuits of FIGS. 1B and 1B'including the recordings on channels C4 to CN will provide a code at theoutput of the binary adder BA therein which will be indicative of thetime lapse between said two signals produced by said multivibratorcircuit.

(B) In FIG. 4, the outputs of any or all of the circuits or logicalswitching circuits AN 2-3, AN 2-4, AN 2-5, may be passed to a Schmittcathode coupled multivibrator circuit and then to pulse transformer PTshown in FIGS. 1B and 1B'. The said outputs present in bit form a numberwhich represents the length of the signal passed through said ANDcircuits. The same may be effected for the outputs of the various NOTswitching circuits of FIG. 4.

(C) In FIG. 7 the output of either clipper CL2 or switching circuitAN2-3 may be passed to a Schmitt circuit and the resulting pulsestherefrom to the pulse transformer PT of FIGS. 1B and 1B'.

(D) In FIG. 8 the output of the switching circuit AN2-4 or N may bepassed to a cathode coupled multivibrator Schmitt circuit CM having itsoutput connected to pulse transformer PT of FIGS. 1B and 1B'.

(E) In FIG. 9, the output of Schmitt circuit CM may be passed to pulsetransformer PT of FIGS. 1B and 1B' or the output of switching circuitAN2-3 to a Schmitt circuit and then to pulse transformer PT formeasuring the respective length or difference signal duration.

The resulting output of the binary adder BA of FIG. 1B' may be passed toa recorder or computing mechanism such as the code matching relay to bedescribed and illustrated in FIG. 10. The output of binary adder BA maybe used as an error or difference signal in machine control. It may beused for example to correct a machine tool or adjust its position toprovide a production or assembly result indicated by the make-up of thepicture signal PB which is closer to an acceptable tolerance orstandard.

FIG. 1C shows a means for effecting automatic control and switching bywhat will hereinafter be referred to as code matching. The apparatuscomprises a magnetic recording member 10 such as a magnetic tape, drumor disc having multiple recording channels C1 to CN carrying saiddescribed sync, picture and gating signals, as illustrated, adjacent toa group of recordings on channels C4 to CN. The recordings comprise apulse code array such as a binary or other code running scale which, ifused to energize the associated reproduction transducers PU to PUN, asshown in FIG. 1B, will provide signals at any instant during saidreproduction in the output circuits of said transducers equivalent to aparticular coded number.

The signals on channels C4 to CN may increase with the length of member10 in a numerically progressing order. Each unit increase in saidrecorded code scale may occupy a particular unit length or anypredetermined length of member 10. Then, each of said lengths isidentified by a particular code which may be used for control purposes.Control signals may be generated and used, for example, to effect suchfunctions as closing a normally open gate having an input from thereproduction amplifier through which the associated picture signal PB isbeing reproduced to pass the part of the picture signal over a furthercircuit, recording of a signal adjacent the code recording. Controlling,timing or programming functions whereby the member 10 is driven at aconstant speed and a particular code is used to represent a particulartime in a cycle.

In FIG. 1C, a series of switches R4 to RN may be manually, pulse, orsignal operated or may be the switches of a card or punch tape readingdevice. Said switches, when closed and opened in the order of thepreselected code, condition the illustrated circuitry. Therefore, asignal will be provided over an output circuit when and only when saidpreselected code appears at the multiple heads PU4 to PUN as shown inFIG. 1B reproducing from the magnetic recording member 10. Saidrecording member may be driven continuously past said heads by a motoror in an intermittent manner by a solenoid actuated ratchet and pawldrive.

When one of the switches RN is closed, a signal is transmitted to aswitching input "I" of a single input, two output bi-stable switch FFNswitching it from a "O" or reset condition to a first, "1" condition.When so actuated, the particular FFN switch switches its input to anoutput circuit which extends therefrom to a corresponding input of an Ninput AND switching circuit AN4N. For example, when the flip-flopbi-stable switch FF4 is in the reset or "O" condition, an input signalsent thereto from reproduction amplifier A4 is passed to the switchinginput of a normally closed monostable switch or NOT circuit N4 openingcircuit N4 and preventing a signal from a power supply PS from passingto its output.

The output of circuit N4 extends to an input of a bi-stable switch FF'4and therefrom to the same input of AN4N that the "1" output of FF4extended to. A logical OR circuit may be provided at the junction of thetwo outputs which connect to the single input to AN4N if said circuitsare not resistance matched.

The bi-stable switch FF'4 is switched to its closed or "1" condition bythe reproduction of a reset signal passed to circuit illustrated input"1" of FF'4. Said reset signal is also passed to the "O" switching inputof FF4 thereby conditioning the circuitry so that a signal will bepassed to the corresponding input to AN4N only when there is no outputsignal from reproduction amplifier A4 (i.e. where there is no signal onchannel C4 at the reproduction head PU4.) A signal transmitted fromamplifier A4 will pass through "O" of flip-flop FF4 to the switchinginput of NOT circuit N4 and prevent the passage therethrough of theconstant output of power supply PS.

The output of switch R4 is also passed to a "O" switching input offlip-flop FF'4 thereby switching FF'4 to open and preventing any signalfrom power supply PS to pass therethrough when in said condition. Withflip-flop FF4 switched to state "1", a signal will be passed to thecorresponding input of circuit AN4N only when a signal is present at thehead PU4 on channel 4. A delay line or relay -D4 may be provided in theoutput of "1"of flip-flop FF4 to account if necessary for the tire ittakes the switches N-3 to N-N to switch if provided in the switchingaction by the action of the corresponding R switches. It is thus seenthat by opening and closing particular or selected of the R switches,provided that all flip-flops FF4 to FFN have been reset to "O", a codearray is set up in relay storage which will provide a signal over theoutput circuit when the same code exists as recordings at the heads PU4to PUN.

As illustrated, the code on channels C4 to CN is a binary code and is ofa numerically progressing order. Consequently, the inputs for activatingswitches R may be derived from a digital computer and may represent thedesired shaft rotation of the power means driving the member 10. Asignal output from circuit AN4N represents the attainment of a degree ofmovement of member 10 as indicated by the code input to the switches R4to RN. Said output signal may be used to start or stop a servo motor SMby activating a relay RE. The relay RE may also be used to pulse asolenoid, to sound an alarm, or to actuate any electronic orelectro-mechanical device, switch, relay or motor. Reset of flip-flopswitches FF and FF' is effected by manually or automatically closing aswitch SW which gates a signal from a power supply PS to a pulsetransformer PT thereby transmitting energizing signals to the respective"O" switching inputs of the FF switches and the "1" inputs of FF'switches.

FIG. 2 shows a section of a recording medium 10 having a number of pulsesignals CS11, CS12, CS13, CS14, CS15 recorded on separate tracks orchannels adjacent video signals PB2, HS2, and VS2. The latter signalCS15 is recorded on channel C9 and is the shortest of all the pulsesignals. While signal CS15 is preferably of a duration in the order often microseconds or less duration when reproduced therefrom, saidduration will depend on what phenomenon it is being used to indicate ormeasure. The C11 to C15 signals are of decreasing length or durationalong member 10 and are shown symmetrical with a transverse line PLextending across and preferably perpendicular to the direction ofrecording and passing through the center of the shortest pulse CS15.This arrangement of recorded signals may be used to indicate theposition or region on which a particular point in the video picturesignal falls or is expected to fall and may be used for measurement orquality control purposes involving said picture signal.

Assume the image from which the video picture signal PB was produced hasa particular characteristic indicative of a position, plane, edge of anobject therein or the beginning of a specific area of said image andsaid characteristic is scanned by the video scanning camera or device asa change in color or light reflectivity. Then, the video signal willchange in amplitude. The change in amplitude may comprise an inflectionin its amplitude if the color or light characteristic of the fieldsuddenly changes. This change in amplitude may be indicatedelectronically by the use of a proper clipping or filter circuit in theoutput of the video reproduction amplifier for the video signalreproduction head. By comparing said clipped signal and noting theposition of the leading edge of said signal in relation to the positionof the CS12 to CS15 signals, its position or the region of its positionmay be indicated electrically.

The CS15 signal may be used to indicate the precise norm or desiredposition of the surface, plane, line or position of the beginning of thearea in the field being scanned. The CS14 signal recording may bepositioned and of such a time duration or length to indicate a range ofacceptable tolerance for said picture signal inflection or imageposition. For example, when the member 10 is moving at video frequencyor the frequency or speed at which the video signal was recorded onmember 10, then the length of the CS14 signal may be such that itsreproduction will occur in a time interval during which the camerascanning beam will travel across a few thousandths of an inch of thesurface of the object or image being scanned which will be equal to thecombination of the plus and minus tolerance permitted for said imageline to be off a desired or predetermined position Pl indicatedpositionally by signal CS15.

It is assumed that an area, benchmark, points or a reference line orplane of the object being scanned is prepositioned in the image fieldand that the object or surface being scanned is at the correct attitudeand distance from the video scanning camera or device. Such a method ofautomatic inspection or measurement may be effected by fixing the videoscanning device or camera to scan a particular area or field. A fixtureor stops are provided in said field being scanned for aligning theobject being scanned so that all objects will have a common base andwill be of equal relative scale in the image field. Thus a particulardegree of sweep of the scanning beam will represent for eachprepositioned object being scanned the same length on the surface ofeach other object scanned.

The length of the CS signals is proportional to a particular length ordistance along any plane in the image field. The positions of theleading and trailing edges of these signals may be electronicallydetected and may be used to indicate the position of a particular line,plane or small area in the image field or to effect the measurement ofsaid line or plane from a predetermined line, plane or point in thefield. As stated, the CS1 signal may be used primarily as a means togate a similar length of the video signal PB to an output circuit andthe position of CS1 will determine what particular length of the videosignal will be gated. Assume that it is desired to indicate or measurethe distance along a video scanning line between two lines oblique tothe beam scanning line which are of different light reflectivity orintensity than the image background. Further assume that the position ofeach of said lines may be indicated as a result of the inflection in theamplitude of the video picture signal by a pulse created as the signalpasses a video clipper, such as a pentode clipper. Then, the CS1 signalwill be provided on member 10 in a position such that, when reproducedtherefrom, it may be used to gate that part of the video signal producedwhen the scanning beam of the video camera crosses said lines.

Since the distance between said lines in the image field may vary fromone sample or image field to the next, if the maximum variation for allsamples being scanned is known, a gating signal CS1 may be provided ofsufficient length to pass the correct section or sections of the videosignal for each field or sample being scanned such that each willcontain that part of the picture signal containing said two lines. TheCS1 signal thus acts to pass only that part of the image signal PB inwhich it is known that the two lines or points will appear regardless oftheir variation from tolerance to the exclusion of all other lines orimages in the total video image field. There may be other lines orimages of similar light intensity in the field which would ordinarilyprevent the comparative or quantitative measurement of the desiredlength or distance in the image field, the PB sections of which wouldhave to be blanked or otherwise discriminated.

The CS12, CS13 and CS14 signals may serve one or more of severalpurposes. They may be used to indicate the actual position and variationfrom a desired position indicated by the center of said signals, of apoint, plane, line or area, as indicated by an amplitude change orinflection in the PB signal occurring in the range indicated by the CS1signal. For example, if the pulse created by the inflection in saidvideo signal occurs between the time the leading edge of the CS12 signalis reproduced and the leading edge of the CS13 signal is reproduced,then said point in the video signal is known to occur in a particulartolerance range or distance from the norm which may be indicated by theposition of the CS15 signal.

Similarly, the range or distances between the leading edges of the CS13and CS14 signals and between their respective trailing edges may besecond tolerance regions and between the respective leading and trailingedges of CS14 and CS15 third tolerance regions. For inspection ofmachined parts, the tolerance regions between CS14 and CS15, forexample, may be indicative of acceptable tolerances between CS13 andCS14 signals indicative of acceptable but also of an impending requiredchange in tool adjustment; between CS13 and CS14 signals indicative of adimension scanned, not passing inspection and quality requirements butcapable of rework, and outside the leading and trailing edges ofreproductions of signal CS13 indicative of complete rejection of thepart and either shut-down of the machine for readjustment or therequisite that the scanning inspection apparatus be checked. The CS12 toCS15 signals may also be used for automatic sorting purposes whereby anobject having a dimension which falls in the range of one of said pulsesignals but not in the range of the next smaller signal may be soclassified or sorted by pulse means to be described.

FIG. 3 shows a magnetic recording member 10 having multiple recordingsthereon and also illustrates associated apparatus for the automaticcomparative measurement of a similar length or lengths of two scanningsignal recordings which are signals derived from photoelectric scanningof moving objects or video beam scanning of image fields. Said picturesignals include a sync or position indicating signal S1 provided on afirst channel C1 of member 10, two picture signals PB1A and PB1Brecorded on channels C2 and C4 and in lateral alignment with each otherand the signal S1, and one or more discrete signals SC11, SC12, etc.shorter than either of said picture signals and recorded inpredetermined positions on member 10 relative to said picture signals.Said reproduced SC signals may be used per se or with signals recordedon still other channels of the recording member to perform one or moreof the various other gating, control and operative functions describedelsewhere in this specification.

In FIG. 3, said SC signals are used, when reproduced, to gate specificand similar lengths of reproductions of the two recorded picture signalsover respective output circuits for automatically comparing thecharacteristics of said similar lengths of said two signals. Forexample, one of said picture signals PB1A may be derived from scanningwhat will hereafter be called a standard image field. Such a standard isdefined as a field of measurement or inspection which to the opticalscanning system of a beam scanning video device contains one or moreimages or image areas which (a) are in a predetermined position in saidfield resulting from determined alignment therein and (b) exhibit otherpredetermined optical characteristics such as predetermined color orlight characteristic.

The other signal, PB1B, is preferably derived from scanning anotherfield containing an image area or areas similar in shape, position orlight characteristics to corresponding areas in said standard imagefield but which may vary in any of said characteristics. Since theamplitude and/or frequency of the picture signals PB1A and PB1B changeas the optical characteristics of the image field being scanned change,said two signals may be compared point by point. Two similar segments orlengths of said signals may thus be compared for amplitude or frequencyvariations by the means provided and the resulting differences in signalvariations indicated by apparatus such as illustrated.

While the method of measurement utilizing the recordings of said twopicture signals provided in fixed relation to each other on a magneticrecording member has numerous advantages, it is possible to perform thesame function by recording said standard image field signal PB1A in afixed or predetermined position relative to sync signal S1, for example.Said second picture signal is provided in the circuitry illustratedduring the same time it is provided in FIG. 3 by the reproductionapparatus illustrated by utilizing the reproduction of said S1 signal totrigger, for example, the sweep of a video storage tube readbeam to scana charge pattern recording of said second picture signal and producesaid second signal over said illustrated circuitry. Similarly, it ispossible to provide both said picture signals recorded on respectivestorage tubes and to effect their simultaneous reproduction by means ofa signal derived by the reproduction of the sync signal S1, whereby themember 10 serves as a signal generating medium for generating said SCsignals at predetermined instants during the reproduction of said twopicture signals.

The method of recording all signals in predetermined positions relativeto each other has numerous advantages. These include the provision of arecording which may be rechecked or rescanned if necessary or changed incharacteristic and which may be filed for future reference or used tomodulate the write beam of a picture tube for visual monitoring. Therecording of at least said standard image field signal on member 10 hasadditional advantages in that it may be one of a multiple of related butdifferent picture signals recorded on said member and may be selectivelyreproduced therefrom adding flexibility to the apparatus and permittingit to be used to perform a multiple of inspection functions relative todifferent image fields or devices.

Assume that the signal PB1A has been derived from scanning a standard orquality-acceptable image field such as derived from the surface of awork member or X-ray structure of an object or subject which conforms tospecified dimensions, surface characteristics or light characteristic.Further assume that said image field contains areas of different lightor radiation intensity or other characteristic which will result insignal variations in a predetermined segment or segments of said picturesignal. Then, the position or positions of similar variations in thesignal derived from scanning field containing images may be measured orcompared. The apparatus shown in block notation in FIG. 3 provides onemethod of comparing the positions of image areas in the standard imagefield with image areas of fields to be compared therewith. Modificationsto said apparatus are possible which will provide not only the same typeof measurement but other inspection functions such as counting, notingimage variations of areas in a particular area or areas of the fieldbeing scanned which do or do not conform in position, light intensity,shape or size with areas of said standard image field.

It is also assumed that means are provided for prepositioning at leastpart of the scanned image area or the object being scanned in thescanning field of the video scanner to produce said picture signal PB1B.Variations in picture signal PB1B represent particular areas of saidimage field provided in a predetermined range or area of possiblescatter so that a basis for measurement and comparison is provided. Forexample, if it is desired to compare the position of one or both of twoareas in a field being scanned with the position of similar areas in astandard or known image field and said areas are permitted to fall atrandom in said field, then one of said areas of one field positionallymay overlap the comparative area of the standard image field which mayresult in an incorrect measurement.

The electrical apparatus of FIG. 3 comprises a multiple of reproductiontransducers PU1, PU2, PU3 and PU4 as shown in FIG. 1B for reproducingthe signals from respective channels C1 to C4. Said transducers areshown in FIG. 1B as being laterally aligned across the member 10 forsimultaneously reproducing aligned sections of signals recorded or saidchannels. The heads may be staggered provided that similar provision ismade in positioning of the respective recorded signals, it beingdesirable to reproduce the start of said two picture signalssimultaneously by their respective transducers. It is assumed that bothpicture signals were initially generated by respective beams initiallypositioned at the same points in each field being scanned or at apredetermined point on the surface of the object being scanned.Therefore, if said image areas being scanned are to the same scale inrelation to the scanning device and are similarly aligned, similarpoints in the resulting picture signals will have similar fieldcoordinate positions.

The signals reproduced by reproduction heads PU1 to PU4 are amplified bymeans of reproduction amplifiers A1 to A4 respectively. The output ofamplifier A2 is passed to the input of a normally open, monostableelectronic gate or switch G1 and the picture signal output ofreproduction amplifier A4 to the input of a second gate G2. Theswitching inputs of gates G1 and G2 receive the output of reproductionamplifier A3 thereby amplifying the signals SC11, SC12, etc. Said gatesG1 and G2 may be any monostable electrical switching device adapted toswitch at the required rate and to effect the completion of a circuitbetween its input and output whenever a signal reproduced from channelC3 is present at the switching inputs and to disconnect said circuits orwhen said signal is no longer present thereat.

Various electron tube and semi-conductor gates are known in the art andmay be used for switches G1 and G2. Thus, if it is only desired tocompare image segments in predetermined areas of said two fields beingscanned or compared, or particular lengths of said respective picturesignals, the positions of the SC signals and their lengths will providesegments of both said signals on measurement which segments wereproduced during beam scanning said predetermined areas of said fields orsaid specified lengths of said signals.

It is also assumed that the picture signals PB1A and PB1B were derivedby beam scanning means which provides a picture signal during scanningwhich varies in amplitude as the beam scans areas of different lightcharacteristic. For example, the field being scanned may contain animage area of one color or light intensity on a field of a differentcolor or intensity. Then, as the beam crosses from said field to saidimage area or vice-versa, the picture signal produced during said beamcrossing will experience an inflection in amplitude.

Scanning and video systems are known which produce a picture signalwhich changes in frequency when the field scanned changes in opticalcharacteristics or radiation intensity. Amplitude change and detectionof said change is utilized throughout this invention for measurementpurposes. However, means for detecting predetermined changes infrequency may also be applied. Thus, if it is desired to compare theposition of an image or part of an area in the standard image field withthe position of a similar area in another field, the locations of therespective inflections in said two signals produced during scanning saidsimilar areas may be compared by comparing their tire relationship inthe output circuits of the respective amplifiers A2 and A4.

The outputs of gates G1 and G2 are passed to respective clippingcircuits CL1 and CL2 which may be standard video diode or triodeclippers adjusted to a desired clipping level. The clipping circuitswill indicate by a signal output therefrom when said inflections in saidrespective picture signals occur. The gates G1 and G2 have the furtheradvantage of limiting the input to the clipping circuits CL1 and CL2 topredetermined lengths of the respective PB signals. The PB signals maycorrespond to segments of said signal produced during the scanning of aspecific area or areas of said total fields. Thus any other areas insaid respective image fields, which areas vary the same degree in lightintensity or characteristic as those being measured, will not confusethe measurements and will not give false results.

The outputs of clippers CL-1 and CL-2 are passed to a logical two-inputAND switching circuit AN1-2 which produces a signal over an outputtherefrom when a signal is present at both inputs. Thus, a line imagemay be in the same coordinate position in the standard image field as inthe other field being scanned. Provided that the other mentionedconditions of recording and reproducing said two signals simultaneouslyand initiating said beam scanning actions at the same point in each ofsaid fields are met, and each of said line images as it is scannedcauses an inflection of short duration in said respective picturesignals, and said inflections cause respective pulse outputs from saidrespective clipping circuits, then an output will be produced from theAND circuit AN1-2 which will be indicative that said two images wherecrossed by respective scanning beams are in the same coordinatepositions in said two fields.

The mentioned indicating technique will suffice if it is merely desiredto compare a point in one scanned field with a point in a second orstandard image field whereby the output of the AND circuit may be passedto a counter or recorder. However, if it is desired to scan a largerarea of a field to determine if one or more points in said field, or oneor more border sections vary in position from a standard, or where aspecific border or line starts to vary from a standard, then furtherindicating and computing apparatus is necessary.

In FIG. 3, the output of AND circuit AN1-2 is passed to the switchinginput of a normally closed monostable switch or logical NOT switchingcircuit N1. Whenever an output from gate AN1-2 is present at circuit N1,said switch will open and break a circuit between its input and output.The outputs of clippers CL-1 and CL-2 are also passed to the inputs of alogical OR stitching circuit O-1, the output of which is connected tothe input of circuit N1. Thus, if either clipping circuit produces anoutput at a time when the other clipping circuit is not producing anoutput, said output signal will be passed through the NOT circuit N1. Anoutput from circuit N1 will thus be indicative that the inflection orchange in the signal PB1B occurs either prior to or after the occurrenceof the respective inflection in the standard signal PB1A.

Physically this may be interpreted as the shifting of the position of aborder or line in an image field being scanned either side of apredetermined position as determined by the position of a similarsection of an image in a standard or quality acceptable field orpattern. If it is desired to determine on which side of the standard ordesired coordinate position, border or line said image beinginvestigated falls, then one of several techniques may be employed. Forexample, one of the two inputs to the OR circuit O-1 may be eliminatedor it may be opened by manual switching means at some time after anoutput has appeared at circuit N1.

FIG. 3 shows technique for determining where in the picture signal PB1Bor said field scanned to produce said signal, an image varies from adesired or standard position defined by the PB1A signal. The techniqueemploys what will hereinafter be referred to as a digital clock or timerreferred to by notation DIT. The timing device DIT is started by pulsinga input F thereof and will produce a pulse code such as a binary digitcode over parallel circuits 22 whenever a trigger input TR of said timeris pulsed. Thus, if the output of NOT circuit N1 is passed to thetrigger input of timer DIT, a signal code is available which indicatesthe time lapse from the time the timer is first energized. The output ofcircuit N1 may be of such a duration and occur during a time intervalwhereby the timing element of timer DIT advances more than one positionor time increment. Then, multiple code signals will be transmitted overthe parallel output circuits 22. By counting the number of said codestransmitted, the degree of which said sampled image area varies from astandard image position may be determined.

The output 22 is shown extending to a computing circuit which may be aninput CO to a digital computer adapted to record or otherwise utilizesaid digital information for computing or control purposes. In a simplerform, stage CO may be a counter or switching circuit adapted to energizeservo devices for performing such functions on work being scanned assorting, marking, assembly or the like. In more complex arrangements,stage CO may be one of a number of digital computing mechanisms adaptedto convert the digital input, after operating thereon, into one or moresignals for controlling various actions which control results from adecision or decisions made by utilizing sad input information. Suchactions as readjusting a machine, stopping, starting, marking and thelike may be controlled by computing mechanisms and will depend on thevalue of the results obtained from scanning.

Other circuitry, hereinafter described, may be utilized to improve orextend the utility of the apparatus of FIG. 3. The use of such apparatuswill depend on the characteristic of the phenomenon being measured andthe design of the computing or measuring circuits CO. For example, theoutput of the NOT circuit N1 may be passed directly to a recordingdevice or to a computer CO' which may be used to record said signals andprovide an output for operating a warning device or servo when saidsignals become greater than predetermined duration or length. The outputof circuit N1 may also be connected to a cathode coupled multivibratorSchmitt circuit CM, the output of which is connected to the input TR oftimer DIT.

The multivibrator Schmitt circuit is adapted to produce a first shortpulse at its output when the leading edge of a longer pulse appears atits input and a second short pulse when the trailing edge of said longerpulse appears at said input. These pulses may each be used to provide arespective coded output over the circuits 22 which are indicative oftheir relative time relationship. Then, said first digital code may besubtracted from the second generated code by employing known digitalcomputing means in stage CO. Consequently, a different signal or codewill be obtained which will be indicative of a difference between thecoordinate position of that part of the image area of the standard fieldbeing scanned and that part of an image area being compared therewith inthe field scanned to produce the PB1B signal. The resulting differencedigital signal obtained from subtracting said two outputs of timer DITmay be recorded and/or automatically compared with a code or numberrecorded in the recording section of the computer CO.

As a further variation in the illustrated measurement technique providedin FIG. 3, a pulse code such as the binary digit pulse code PC' onchannel C5 of member 10 may be provided, reproduced and passed to thecomputer CO. The code PC' is reproduced by reproduction transducer PV5and amplified by reproduction amplifier A5 prior to being transmitted tocomputer CO. Code PC' may represent, for example, in binary digitalnotation, a number equivalent to the maximum permissible differencebetween the mentioned two pulse code outputs 22 resulting from said two,leading-trailing edge signal created short pulse outputs of said cathodecoupled multivibrator.

By matching said two digital codes (i.e. the reproduction of code PC'and the difference signal computed by computer CO) it can beautomatically determined if the variation in that part of the positionof that part of the article or image being scanned and the position ofassociated part of the standard image is greater than the degreespecified by the code recording PC'. The difference signal or numberwhich has been obtained by subtracting said first input number fromtimer DIT to computer CO from said second input may be subtracted fromthe digital signal obtained by reproduction of the recording PC'. Theresult is a number which indicates how close the deviation in theposition of said article or image area being scanned is to a maximumpermissible deviation from a standard position. This latter result maybe used to effect the positioning of a tool or other device by operatinga servo motor through an equivalent degree of motion or angular positionproportional to said difference signal or code.

The signal PC' of FIG. 3 may also be replaced by one or more laterallyaligned code recordings of the type referred to by notation PCillustrated in FIG. 1. Additional recording channels C5 to CN may beprovided with means for simultaneously reproducing a particular array ofpulse recordings at one time. For example, a digital code signal outputmay be provided over parallel circuits to computer CO at a particularinstant or short time interval in the measurement cycle. Then, saidcodes PC may vary in value from point to point along member 10 and maybe used to perform or effect different operations or functions.

Multiple PC codes may be provided to indicate maximum permissiblevariations in the positions of the standard image and that beingmeasured. Then, each PC recording may be used to indicate the variationin the position or dimension in a particular part or dimension of thetotal image or article being scanned. For example, the maximum variationor permissible tolerance from a specified position of a first object orcomponent assembled on a chassis may be X inches and of a second object,Y inches. A first code PC is provided opposite or just prior to thoseparts of the picture signals produced during beam scanning said firstobject which is indicative of said first permissible maximum variation.A second code PC is provided in a position or positions along member 10to be reproduced just prior to or during those parts of the picturesignals produced during beam scanning said second object. The firstoutput of the cathode coupled multivibrator or the signal SC reproducedfrom member 10 may be used for switching purposes in the computer CO.For example, switching the associated PC code reproduced from member 10during the time interval defined by said SC signal may be switched to aparticular storage unit such as a relay storage where it is held andused for comparison with the associated output of timer DIT. Furtherdetails of such a switching function will be described hereinafter.

FIG. 4 shows magnetic recording means and associated reproductiondetermining one or more of the following phenomena:

(a) If a given image portion or area in a field being scanned falls in aparticular position in said field or if reference points, lines orplanes of a given image fall in predetermined positions in said field,

(b) Where in said total field or how far off a reference point, line orarea in the scanned field a given point, image area or line falls.Examples of the operations of the above referred to scanning meansinclude such investigative functions as determining if the border of anarea or areas such as the edge of a workpiece, part of assembly fallsalong a particular array of coordinates; determine if the workpiece isprecisely positioned on an assembly or is fabricated to tolerance. It isassumed that another surface or area of said workpiece is in a fixedposition in said field to establish a benchmark or base for saidcomparative measurement,

(c) The means of FIG. 4 may also be used in determining if lines orareas on a map, scope, drawing or photograph fall along predeterminedpositions. It is again assumed that part of said map or drawing is in areferenced position in said field being scanned.

The arrangement of FIG. 4 may also determine the degree of variance ofphenomena such as described above from a predetermined position orpositions in said field; and if any other image phenomenon which ischaracterized by a variation in light characteristic exists in a givenscanning field.

For the purpose of simplifying the description of the signal recordingarrangement and apparatus of FIG. 4, reference is made to FIGS. 2 and4'. In FIG. 2, multiple pulse signals are provided each on a differentchannel of the magnetic recording member 10 to indicate the position ofa change or inflection in a video picture signal by noting during whichof said pulse signals said variation is reproduced. Similar recordingarrangements are provided in FIG. 4 at various positions illustrated assignals P1 to PN on member 10 which represent precise coordinatepositions or distances recorded from the start of the picture signalrecording where changes such as inflections in said picture signal willoccur if the surface being scanned is precisely positioned relative tothe scanning apparatus when the field scanned to produce the PB signalis similar to a standard image field.

Thus, at each of the P coordinate positions, multiple pulse signals areprovided which bear the general notations SC1-N, SC2-N, SC3-N. The SC3-Nsignals are located at the P positions. When said inflection in said PBsignal is reproduced simultaneously with the corresponding SC3-N signal,the condition may be indicated by use of a logical switching AND circuitwhich produces an output when said condition occurs. Said output signalindicates that the line or area being measured falls at a predeterminedlocation or coordinate position in the image field.

Reference is also made to FIG. 4' which shows a fragment of an imagefield IFP being scanned. The horizontal lines ST-L represent the traceof a raster scanning beam. The recording means and apparatus of FIG. 4may be utilized to determine if an area such as the band LN ispositioned in said field IFP with its borders at predeterminedcoordinate positions therein. Band LN may be such phenomena as thesilhouette image of a machined part, a line or curve on a graph, map ordrawing, etc.

For many measurement functions, if another surface of said machined partis prepositioned in the field IFP or prepositioned relative to thescanning device, a maximum variation of an image thereof such as band LNfrom a predetermined position in said field may be determined and notedby means of measuring the lengths of the SC1-N signals. If the area LNis of a different color or light intensity than the surrounding area, itwill cause, when scanned, a change in the resulting video signal. Such achange may be inflection in amplitude in that part of the signalproduced when the camera scanning beam scans said image line. Themaximum expected shift in the position of band LN either side of thepredetermined position illustrated is indicated by the length of thelongest signals SC-N on channel C3. If the line in the image fieldshould fall beyond the band or area having the width SCN in FIG. 4',then that part of the picture signal PB obtained when the camera beamscanned line LN will not be gated by the associated CS signal.

From FIG. 4', it is noted that a definition of the CS signals of FIG. 2is that they are pulse signals of such a length, duration and positionon magnetic recording member 10 relative to the associated video picturesignal PB that, when said CS signals are reproduced therefrom, theirpresence at the switching input of a normally open monostable electronicgate may be used to gate only those segments of the PB signal which wereproduced when the video scanning beam scanned the band area ASCN, ASC2Nhaving the width SCN as shown in FIG. 4. A narrower band area ASC2Nhaving a width SC2N and centered within the larger band area, similarlydefines the SC2N signals of FIG. 4.

While these band areas are assumed to be fixed in the field IFP andprovide increasingly smaller regions which approach the area or line P,the actual position of the image area or line LN may shift from onesample being scanned to the next and may fall on either side of the lineP of FIG. 4. As stated, the area of maximum expected dispersion of bandLN is assumed to have the width SCN. Whereas, in FIG. 4' it is assumedthat the line LN may shift in its absissa or X value only from Xp+SCN/2to Xp-SCN/2 where Xp is the X coordinate value of the line P, otherscanning arrangements may have a line image or area of any predeterminedshape. Whereas in FIG. 4, the SC3-N signals which indicate the desiredor basic position of the line or band LN are of equal duration and areequi-spaced, for other measurement problems, the spacing of said SC3-Nsignals will depend on the shape or other characteristic of the line orphenomenon being scanned and the type of image scanning employed toproduce the picture signal.

In the upper left hand corner of the image field IFP in FIG. 4', theimage of a line LA may comprise a mark on the article, map or surface,part of the edge of said image or some other characteristic of saidimage being scanned which may be used to indicate if said article orsurface being scanned is aligned in the field IFP and/or provided in thecorrect scale therein. The image line or area LA will produce changes orinflections in the PB signal and these may be compared for position inthe picture signal with short pulses recorded on member 10. Said pulsesare shown on channel C6 of FIG. 4 and are referred to by the notationsCS6-1, CS6-2, etc. The pulses CS6-N may all be produced simultaneouslywith a corresponding pulse caused by the inflection in the video signalPB each time it scans the line LA. Then, by the provision of logicalswitching circuits in the outputs of the reproduction apparatus and aclipping circuit for clipping said inflections in the PB signal, anautomatic indication may be attained that the object or surfacecontaining the line or optical phenomenon LN is properly aligned in theimage field and/or provided to correct scale therein. If theseconditions are not met, a warning device may be actuated to indicatethat corrective action must be taken by a human operator beforeautomatic scanning may be continued.

The apparatus of FIG. 4 is illustrated in block diagram notation for thepurpose of simplifying the drawings. Various standard electricalcomponents such as reproduction amplifiers Al to A6, video clippingcircuits CL, gates G, logical AND switching circuits AN, logical NOTswitching circuits N and the like are provided and are known in the art.It is assumed that each of these circuits is provided with a powersupply of sufficient magnitude. Similarly, these circuits are assumed tobe capable of switching at the required frequency for effectingprecision in measurement.

The circuitry illustrated in the block diagram of FIG. 4 may be utilizedto determine (a) if the surface, article, map, drawing, photograph orother object containing the image LN to be scanned is to the correctscale in the image field IFP, (b) if same is correctly aligned relativeto the optical or flying spot scanning system of the video deviceeffecting said scanning, and (c) just where in the area of possibledispersion said LN image falls. Multiple magnetic reproduction heads PU1to PU6 are provided aligned across the tape 10 over channels C1 to C6for simultaneous reproduction of any of the illustrated signals.

The head PU2 rides against channel C2 containing the picture signal PBand the signal reproduced thereby is amplified in a reproductionamplifier A2. From amplifier A2, the signal is passed to a clippingcircuit CL2 adjusted in clipping level to pass only those parts of thePB signal of a desired amplitude such as the inflection portionsgenerated as the scanning beam scans lines LA and LN. The output ofclipper CL2 is passed to a monostable, normally open electronic gate G2having a switching input from amplifier A3 and logical circuit AN6-2 isfrom the amplifier A6 of the reproduction head PU6, so that the signalsCS6-N will be passed thereto. If the reference line or area LA in theimage field is permitted to be a predetermined degree off scale or off aspecified position or basic position in the field IFP, the permissablescatter may be accounted for in the length of the CS6 signals.

The output of amplifier A6 is also passed to a delay line D6, the outputof which is connected to the input of a logical NOT circuit N6. Theswitching input to NOT circuit N6 is from the output of AND circuitAN6-2. Thus, if a signal is reproduced from the track C6 at a time whenno signal is produced at the output of clipper CL2, an indication thatthe reference line LA on the object or surface being scanned is not at apredetermined position or attitude in the image field IFP will produce asignal at the output of the NOT circuit N6.

The delay circuit or line D6 is provided of a time duration to accountfor the time required to switch circuits AN6-2 and N6 although for manyapplications it may not be required. If signals are simultaneouslyreproduced at the output of clipper CL2 and amplifier A6, AND circuitAN6-2 will produce an output and switch the normally closed NOT switchN6 to open so that the signal from amplifier A6 will not passtherethrough to an alarm or other device AL6. Device AL6 may be a relaywhich, when energized by an output from NOT circuit N6, is adapted toeffect such actions as the stopping of the measuring apparatus,rejection of the part or article being scanned, etc., by energizing anelectrical device such as a relay actuated solenoid.

Circuitry is provided to determine where the image of LN falls in theimage zone referred to by notation ASCN in FIG. 4. Respectivereproduction heads PU3, PU4 and PU5 scan channels C3, C4 and C5 andreproduce the illustrated signals therefrom. The reproduction amplifiersA3, A4 and A5 amplify the signals reproduced by their respective heads.The output of amplifier A3 is passed to the switching input of gate G2thereby closing said gate while present thereat and permitting anysignal or signals produced at the output of clipper CL2 while said gateG2 is closed by the presence of a reproduced SCN signal thereat to passto three circuits including inputs to AND switching circuits AN2-3,AN2-4, and AN2-5.

The other input to circuit AN2-3 is from amplifier A3. When clipper CL2produces an output at the same time that one of the SCN signals onchannel C3 is being reproduced, an output will be produced from circuitAN2-3 indicating that the change or inflection in the PB signal causedby the scanning beam sweeping across the area LN falls in the regionASCN of the scanned image field. The output of circuit AN2-3 may bepassed to a counter, recording device or further logical switchingcircuit 12. The output of amplifier A3 is also passed to the switchinginput of a NOT circuit N2-3, the signal input to which is derived fromclipper CL2. Thus, if the area or line LN falls outside of the areaASCN, such that the change in the PB signal occurs and is passed toclipper CL2 at a time when no signal is present at amplifier A3 to bepassed to open circuit N2-3, sail signal clipped by CL2 will passthrough circuit N2-3 to a circuit I2-3 which may be an alarm, recorderor relay adapted to energize a counter or actuate a solenoid or otherdevice.

The output of switch G2 is also passed to one input of a logical ANDswitching circuit AN2-4. The other input to switch-circuit AN2-4 is fromamplifier A4. Therefore, if an SC2N signal is reproduced at the sametime an output is produced from clipper CL2, a signal indication isobtained that the line LN falls in the region or area ASC2N having thewidth SC2N. The width SC2N is shown in FIG. 4' as a narrower band orarea closer to the required position of line LN at X=Xp, Y=O in FIG. 4'.The output from switching circuit AN2-4 may be passed to a counter,recorder or relay 14. If relay 14 is a pulse counter, it may be adaptedto produce a pulse over an output circuit upon receipt of a particularnumber of pulses from switching circuit AN2-4. If LN is a curved line orband or is oblique to the horizontal X- axis of the image field, apredetermined number of pulses produced from switching circuit AN2-4will indicate that a particular part or percentage of the total line LNfalls within the area ASC2N.

It may be desired to discover where in the image field the line LNdeviates in its position and if it falls outside of a given limitdefined, for example, as the band area ASC2N. Assuming that said linecan vary from one sample scanned to the next in a manner whereby part ofsaid line may fall within said given area and part beyond said givenarea, a code indication of where said deviation occurs may be derived asfollows:

A pulse counter PCO having a counting input PC is connected to anormally inactive pulse generator PG. The trigger input to the pulsegenerator PG is from the output of reproduction amplifier Al whichreceives the reproduction of the S1 signal on channel C1. Since the S1signal is indicative of the reproduction of the start of the PB signaland is used to trigger the pulse generator PG, the number of pulsesproduced by pulse generator PG after being so triggered is an indicationof the length of the recording member 10 moved past the reproductionheals. Hence, it may be used to indicate the position of a particularpoint in the picture signal PB such as a deviation from tolerance.

The pulse count or pulse signals received by said counter activate saidcounter for indicating where in said video PB signal or in said imagefield said deviation or other occurrence take place. The phenomenonmeasurable by the apparatus of FIG. 4 is a point or area in the imagefield IFP where the line LN first extends beyond o leaves predeterminedarea ASC2N. This may physically be interpreted as a deviation fromtolerance, a change in a predetermined image condition, or an imagechange such as a step in the shape of a manufactured part.

Said indication of position may be attained as follows: The counter PCOis assumed to be initially set at zero and is adapted to start to countupon receipt of a first pulse from the pulse generator PG which istriggered by reproduction of an S1 signal as the recording passes headPU1. When a second input PCR to the counter PCO is pulsed, said countereither stops counting or provides signals therefrom indicative of thecount received prior to energizing input PCR by means of said pulse.Said signals are transmitted to a circuit I6 which may ba a recorder,relay, part of a logical computing circuit or other device.

In FIG. 4 the input PCR is adapted to receive a pulse when theinflection or change in the PB signal, caused as the beam of thescanning camera first sweeps across the area LN, is reproduced by headPU2 when part of the SC2N signal associated therewith is not reproducedtherewith. The pulse transmitted to input PCR is indicative of thiscondition because it is the output of clipper CL2 and can only be passedthrough a normally closed NOT gate NCR when there is no signal at theswitching input of said gate from amplifier A4. An output through NOTcircuit NCR indicates that the line or border of the area LN in FIG. 4'falls outside of the limits or area defined by the SC2 signals yet, dueto the gating action of the SC1 signals when said line falls within thelimits defined by the signal on channel C3.

Two other functions which may result when a signal is produced andpassed through circuit NCR are also illustrated. The output of circuitNCR may also be passed through a time delay switch or delay line D2 tothe resetting input RT of pulse counter PCO to automatically reset saidtimer to condition it for the next measuring function. The output ofcircuit NCR is also connected to a relay RE6 which may actuate a warningdevice, solenoid or motor for causing such an action as rejection of thearticle being inspected, stopping a production machine, etc. The outputof the pulse counter PCO may be provided on a single or multipleparallel circuits for transmitting a parallel pulse code therefromwhenever input PCR is energized to the input of stage I6 which may be arecorder, computer, switching circuit, relay or other device.

The pulse generator PG of FIG. 4 may be eliminated from the circuitry asfollows: Instead of recording a single pulse S1 on channel C1, multipleequi-spaced short pulses are recorded thereon preferably extending thelength of the PB signal. The length of these pulse signals SN willdepend or the length of the PB signal. If the heads PU1 to PU6 arelaterally aligned across a magnetic tape 10, then the first signal S1will preferably be positioned at or near the start of the PB signal. Thenumber of SN signals which pass and are reproduced by the head PU1 atany instant during the reproduction will be an indication of the lengthof the PB signal which has been reproduced up to that instant. Theoutput of amplifier Al may be thus passed directly to the pulse countinginput of a counter such as counter PCO which has been set at zero andsaid counter may be stopped and caused to read out a value of the totalnumber of counts received by an input such as from circuit N6. Then, thetotal pulses received until receipt of said latter input will be anindication of the length or position of the PB signal at which saidlatter pulse was received.

In FIG. 4a a code generating means is provided in place of the pulsecounter PCO of FIG. 4 to indicate the position or positions of specificimages or parts of images in the total image field represented by thevideo picture signal PB. For example, various measurement, computing orcontrol functions may require the automatic indication by means ofelectrical signal means indicating the position of a line in the imagefield or a portion of a line in a predetermined part of the image field.If the field IFP of FIG. 4' is considered the X-Y plane of a coordinatesystem and the origin is predetermined by the coordinates as X=O,Y=O atthe lower left hand corner of said field, then any point in said fieldmay be referred to as having positive Y coordinate.

A means for determining the coordinates of a point in field IFP in FIG.4 of a particular point in the PB signal is to initiate counting whenfirst reproducing the PB signal by gating the output of a pulsegenerator PG and noting the total count or number of pulses generatedthereafter at any instant. However, device 16 connected to the output ofcounter PCO may be a digital computer which is adapted to utilize theoutput of counter PCO for automatic computational purposes. Then, saidoutput is preferably provided in binary digital pulse form. Counters areknown in the art and will provide a binary pulse code output at anyinstant during their operation by pulsing their input. If counter PCO issuch a digital output counter, a pulse transmitted thereto from NOTcircuit NCR may be utilized to indicate, by means of binary codes,variations in the picture signal PB recorded on channel C2 of member 10.

In FIG. 4a means are also shown for providing an instantaneous binarypulse code output on parallel circuits to the input of a digitalcomputer CO. The said code is an indication of the location of aparticular point in the picture signal. Depending on the circuitryemployed to energize said code producing apparatus, said code may serveas an indication of the location of a particular change in said picturesignal thereby digitally indicating the position of a particular part ofthe image in the field IFP.

In FIG. 4a, an analog to digital converter ADC of conventional design isemployed to provide a digital pulse code on parallel circuits CKC whichare connected to the input of a digital computer CO. The converter ADCmay comprise a constant speed motor driven and a shaft switching devicehaving multiple brush contactors which sweep a coded contact area of acoded disc to produce a digital code over parallel circuits indicativeof the position of said shaft at the instant an input TR is pulsed. Theoutput of the amplifier Al is connected for reproducing the recorded S1pulse and passes said pulse to the starting input S-ADC of the converterdriving motor to start the cycle. It is therefore assumed that the shaftof said converter is at zero position prior to starting.

The code triggering signal to the trigger input TR of converter ADC mayoriginate from any of the logical switching circuits or gates of FIG. 4depending on what is desired to be indicated by means of a digital codesignal. For example, the image phenomenon in the field IFP may comprisea line such as LN of FIG. 4' or a simple analog curve and it is desiredto indicate by coded signal means the coordinate points in said fieldwhere said curve or line falls. Then, the input to input TR is connectedto the gate G2 of FIG. 4. Each time an inflection occurs reproduced inthe picture signal PB, a parallel digital code will be produced over themultiple parallel circuits CKC and transmitted to the computer CO.

It may be desired to indicate where the area AC, for example, variesfrom the predetermined area position as indicated in FIG. 8'. Then, thepulse input to input TR may be derived from one of the outputs of thelogical AND switching circuits AN2. The selection of which output to usewill depend on which of the limits denoted by the signals SC1, SC2, SC3,etc. it is desired to measure variations relative to. The output of NOTcircuits N23, N24, etc. will provide a code indication at the computerby activating to the input TR of converter ADC when a change in the PBsignal occured resulting from the area scanned falling outside thelimits defined by the signals on channels C3 and C4.

The input RE-ADC to the analog/digital converter ADC ADC is connected toa reproduction amplifier A7 which reproduces a signal from a seventhchannel of recording member 10 (not shown). The seventh channel signalis positioned thereon to be reproduced after the reproduction of the PBsignal and is used to either stop converter ADC at its zero position oractivate a servo which drives converter ADC position to a shaft thereofat said zero position. If the switching shaft of converter ADC isadapted to make one revolution during the time it takes to reproduce thePB signal, then a limit switch may be provided mounted adjacent saidswitching shaft of converter ADC adapted to be closed when onerevolution of said shaft has been made and to thereby stop said drivingmotor at said zero position. Pulsing the control S-ADC during the nextcycle by means of a signal reproduced from channel C1 may be used tobypass switch RE-ADC and start said converter driving motor to start thenext inspection cycle.

FIG. 4B is a diagram showing further details of a digital clock o timerof the timer type DIT utilized in FIGS. 3 and 4. As stated, the digitalclock is adapted, when operative, to transmit a digit binary codetherefrom at any instant after starting when an input TR is pulsed. Saidcode is indicative of the time passed from the starting of said clock.If the cycle of timer DIT is activated at a predetermined time duringthe reproduction of the picture signal PB, the position of any point insaid PB signal may be indicated by generating a pulse signal at theinstant said point in said picture signal is reproduced and by passingsaid pulse signal to the input TR of timer DIT. The resulting codetransmitted over parallel circuits 22 will be indicative of the timesaid clock was pulsed.

The digital clock of FIG. 4B is electro-mechanical and is a modificationof the conventional shaft position encoder in that it is driven afterstarting at a constant speed. The clock DIT indicates unit time lapsewhereas the conventional encoder is a variable speed device which isdriven by a variable speed motor the shaft of which is speed controlledby an analog signal. The clock DIT may utilize certain components of aconventional shaft encoder; namely, a shaft digitizer assembly ADC'having the conventional code disc therein and readout means. Assumingthat digitizer ADC' is a photoelectric type of encoder, it may containthe conventional code disc driven by shaft 16. It also has a readoutflash light source which is energized when a signal is present at inputTR, a radiation limiting slit between the code disc and light, a slitsystem on the other side of the code disc and a multi-elementphotoelectric PBS cell on the other side of the slit system.

The cell elements which receive light through the disc pass pulsesignals over the output circuits 22 to computer CO. These elements,while not illustrated in FIG. 4B are known in the art and are part ofthe encoder section of the type 309-13 electric shaft position encoderproduced by the Electronic Corp. of America. The shaft 16 is driven by aconstant speed motor 12 through reduction gears preferably of a ratio of100 to 1 or greater. The ratio depends on the time constant of the clockand the running speed of the motor 12. The motor 12 may be any constantspeed, rapidly accelerating motor.

During the time of acceleration, accurate code signal indications oftime lapse can only be obtained if the acceleration is constant oroccurs always in a predetermined manner. If the motor is provided toaccelerate at a constant rate or always in a predetermined manner andcontains the necessary controls to maintain a constant speed thereafter,it may be calibrated so that a particular pulse code that is generatedon the outputs 22 with the shaft 16 initially provided at a zero setpoint will always indicate by code the same time lapse from saidstarting. Known automatic control apparatus 12 is used for rapidlyaccelerating said motor in a predetermined manner and includes controlmeans for maintaining the speed of said motor constant thereafter.

The starting and stopping of clock DIT and its reset to zero may beeffected by a combination of switches including a pulse actuatedflip-flop switch for starting and stopping the motor 12. The switch isindicated by the blocks having notations F and S. When input F ispulsed, a circuit is completed between a power supply PS and the motor12 and/or its constant speed control. When the input S to the flip-flopswitch is pulsed, said switch switches to open, thereby cutting off thepower supply. In the apparatus of FIG. 4, if the input to F is derivedfrom amplifier Al and if member 10 is driven at constant speed, then atany particular instant after input F is energized by the reproduced S1pulse, a particular code will be transmitted from the encoder and saidcode will be indicative of said time interval.

The output of the converter ADC' consists of multiple parallel circuits22 over which said digital pulse code is transmitted whenever an inputpulse appears at a line 20. The input line 20 extends from the gate GSand the output code from digitizer ADC' effected when line 20 isenergized will indicate the point at which an inflection occurred in thePB signal.

The digital timer or clock DIT may be reset to zero as follows: Abi-stable solenoid 21 is mounted adjacent the shaft 16. A cam projection18 is provided on shaft 16 which during normal operation of the devicerotates and clears the retracted shaft 26 of the push pull solenoid 21.The solenoid has two inputs F and R. When input F is pulsed its shaft 26projects and when input R is pulsed shaft 26 retracts. Mounted on theend of shaft 26 is a limit switch 28 which is projected into the path ofcam 18 when input F of solenoid 21 is pulsed. The limit switch 28 isprovided in circuit with a power supply PS and when closed as it engagescam projection 18, a signal thereby transmitted to the stop control S ofmotor 12 and input R of 21. The solenoid shaft 26 is thus retracted andthe motor 12 stopped with the shaft 16 provided in a predetermined orzero position. A delay relay 30 in the circuit of limit switch 28 andinput R of solenoid 21 may be used to delay the retraction of shaft 26so that the shaft 16 may come to rest against shaft 26. The pulsetransmitted to input F of solenoid 21 is derived from an amplifier A7which amplifies signals recorded on a seventh channel C7 of the member10. The seventh channel signals are provided to indicate the end of theparticular recording or desired computing function.

In FIG. 5, a signal recording arrangement is provided on a magneticrecording member 10 and is applicable for operating on or gatingparticular lengths of a video picture signal which correspond to thoseparts of the video picture signal PB derived during the beam scanning ofa particular area or areas of the image field or object being scanned.The recorded signals of FIG. 5 comprise a sync signal S1 provided on afirst recording channel C1 for indicating the position of a videopicture signal PB on a recording channel C2. Multiple pulse gatingsignals SC1, SC2, SC3 . . . etc., preferably of predetermined duration,are provided on a third channel C3 in predetermined positions adjacentthe PB signal. The SCN signals are preferably of a length and/orpositioned relative to the picture signal PB such that they may be usedto gate or effect operations on similar lengths of the PB signal. If thelength, spacing and positions of the SC signals are predetermined, thenthat part of the total video picture signal PB which was produced duringthe camera beam scanning of a particular area of the total field beingscanned may be gated thereby or operated upon. The segments of the PBsignal which are so gated will be determined by simultaneouslyreproducing the PB signal and the SC signal.

If the reproduction heads are laterally aligned across the magneticrecording member 10, as illustrated, then each SC signal may be used togate an equivalent adjacent length of the PB signal. For gating oroperating upon those segments of the PB signal created during the videoscanning of a specific area or areas of the total field being scanned,the lengths, spacings and positions of the SC signals relative to the PBsignal will be determined by the shape of the selected area or patch ofthe total field being scanned and by the type of scanning employed. Forexample, raster scanning may be employed across a rectangular scanningfield. Consequently, a rectangular area or patch in said total fieldwhich has its sides parallel to the borders of the total field will berepresented in the PB signal by a series of equi-length, equi-spacedsegments of the picture signal.

The segments of said picture signal may be reproduced and scanned orotherwise operated upon by having similar lengths of equi-spaced gatingsignals SC recorded on channel C3 and by reproducing said SC signalssimultaneously with the picture signal The presence of the reproduced SCsignal at the switching input of a normally closed electron tube gatewill gate an equal length of the PB signal. By predetermining thelengths, spacings and positions of the recorded SC signals, anyparticular area or areas of the total field being scanned may be gatedin this manner or otherwise upon. The SC signals may be provided by apulse generator of known design. Either reproduction of the sync pulseS1 or the first part of the picture signal may be utilized to triggerthe operation of said pulse generator to correctly provide the SCsignals for recording onto channel C3.

Still another means for providing SC or CS signals on member 10 of thecorrect length, spacing and position may comprise scanning an object orimage field by beam scanning means and passing the resulting videopicture signal to a beam storage tube and recording it on the storageelement thereof. Next, the recording member 10 is driven past itsrecording and reproduction heads. Reproduction of the S1 signal is usedto trigger the read beam of said storage tube. The resulting output ofsaid tube is passed to a clipping circuit of the type described. Theoutput of the clipper is recorded on channel C3 as a series of discretesignals. If the signal recorded in the storage tube is derived byscanning a mask or map having position predetermined black or whiteareas of sufficient light contrast on background fields and said mask ormap is correctly positioned in the scanning field of said beam scanningmeans and provided at the proper image scale, then SC signals of thedesired length, spacing and position may be generated and recorded onchannel C3 by selection of the correct mask pattern.

A preferable means for providing such a mask is as follows: An imagefield IF is shown in FIG. 8' at the scanning plane of a video scanner orvideo camera optical system. Raster scanning is utilized in FIG. 8' andthe scanning field is assumed to be rectangular. The horizontal lines STare traced by the video camera scanning beam which sweeps across severalareas A-A, A-B and A-C. Said areas are each crossed by a number ofhorizontal scanning sweeps. Each of said areas are assumed to havedifferent light characteristics or color than the background BF of saidfield IF. To determine if the area A-C falls within a specific band areaA-C' of the field, the apparatus of FIG. 4 may be used to effect saiddetermination. The signal recordings of FIG. 5 consist of a series ofgating signals SCN provided of equal length and equal spacing along therecording member if the area A-C' is rectangular and if the borders ofsaid scanned area are parallel to the borders of the image field IF.Each time the beam scans a path ST and crosses the leading edge E1 ofarea A-C, an inflection occurs in the amplitude of the picture signal.If the background area to the right of image area A-C is the same lightintensity as the area on the left side of the A-C picture, said signalwill exhibit the same amplitude generated before scanning A-C when thebeam sweeps past the trailing edge E2 of area A-C. The area A-C mayrepresent any optical phenomenon such as a cutout in a panel, acomponent assembled on a device having a general surface of differentcolor than area A-C, the cross section shadow or end view of an object,one object or area in a field of many such as illustrated by areas A-Band A-C.

The area A-C of FIG. 8' may be positioned in a known position in thefield IF and it may be required to measure or indicate only thepositions of similar shaped areas in other scanned image fields. Then,the signals to be recorded on channel C3 of FIG. 5 may be obtained byplacing a mask over the areas A-A and A-B of essentially the same lightcharacteristic as the background of said field, scanning the field IFwith a video image scanning camera such as a vidicon or iconoscope tube,passing the resulting picture signal to a clipping circuit such asclipper CL-2 of FIG. 4 and recording the output of said clipping circuiton the magnetic tape 10. The recorded signal S1 is used to start ortrigger beam scanning of the field IF.

Hence, the phenomenon to be measured is recorded and may be reproducedat the correct instant so that the signals SC1, SC2, SC3 . . . SCN maybe used to gate only those parts of the picture signal PB generatedduring the scanning of the area A-C while excluding signals generated oscanning areas A-A and A-B. In order to generate and record, signals SCNon member 10 for gating portions of the picture signal PB generated inscanning an area A-C' which area is larger than A-C and has a marginalarea around area A-C to account for permissible small shifts in theposition of area A-C from one workpiece or specimen being scanned to thenext and to generate gating signals modified to account for permissibleshifting or movement of area A-C in the image field, the optical systemof the scanning device may be enlarged the necessary degree to make thesides or borders of the area A-C fall on the coordinate lines LE and TEwhich respectively represent the sides of the area A-C' and determinethe leading are trailing edges of said SCN signals. After effecting saidenlargement of the image area A-C and masking of the areas A-A and A-Bso that the background of image field IF is essentially of one lightcharacteristic, the modified field may be scanned and the picture signalpassed to a clipping circuit the output of which is recorded asdescribed to provide the SCN signals on member 10.

FIG. 6 illustrates a recording arrangement and associated transducingapparatus for reproducing and/or modifying a portion or predeterminedportions of a video picture signal PB recorded on a magnetic recordingmember or tape 10 whereby control of said reproduction or signalmodifying is effected by one or more signals recorded in predeterminedpositions relative to said PB signal. In FIG. 6, a single control signalCS1 is shown provided on channel C3 of the recording member 10 adjacentthe PB signal. Signal CS1 is in such a position whereby it may be usedto gate or otherwise effect an operation on a similar and predeterminedlength of the PB signal.

The signal S1 on channel C1 may be used to record either the PB signalor CS1 signal in a predetermined relative positions, one after the otheris recorded thereon. The CS signal may be passed as described to theswitching input of normally open gate G2 after being reproduced byreproduction transducer PU3. When switch G2 is closed by the signalreproduction of the CS recording passed thereto, that part of the PBsignal present at reproduction head PU2 will be passed through said gateG2. A particular segment or segments of the PB signal such as thesegments produced during the beam scanning of a particular area in theimage field may thus be gated and passed to a circuit DCK which isadapted to operate in a predetermined manner on said gated segments ofthe reproduced picture signal by means of the gating signal or signalsrecorded on channel C3.

The circuit DCK is provided to perform on a or more of a number offunctions on the gated segments of the PB signal passed thereto. Ifsegments of the PB signals are gated by multiple pulse signals on C3 ofpredetermined length and positioned such that said gated segmentscorrespond to the picture signal sections generated during the scanningof a particular area of the field being scanned, then functions such asamplification attenuation or erasure of the gated signal portions may beeffected by operation of circuit DCK to produce a modified video signalwhich will provide a corresponding change in the image field generatedthereby. Gate G2 may be operated to close and pass predeterminedportions of the video signal by gating signals derived, as hereinaboveprovided, from clipping portions of the reproduced video picture signalitself (i.e. the output of head PU2) which may fall above or below acertain level.

If the output of delay DT' is connected to recording head RH2, gate GTmay be operated to close by the same clipped gating signals. Thus eitherthe output of the signal changer circuit DCK or the picture signalgenerating storage tube ST may be passed to recording head RH2 afterappropriate delay introduced by delay lines DT' or DCK is effective inpresenting the new or modified picture signal segment at the recordinghead RH2 at a time that either the clipped portion of the recordedpicture signal PB or the portion defined by signal CS1 is present atrecording head RH2.

The new or modified video signal portion may either be recorded directlyover the segment of the video signal recording it is to modify orreplace or on the appropriate length of the channel C2 which has beenerased. Such erasure may be effected by either passing the clippedportion of the reproduced video picture signal or the reproduced CSsignal(s) through a delay line D3 to the switching input of a normallyopen monostable electronic gate GE which gates a power supply PS toenergize a magnetic erase head EH2.

The delay period of delay D3 is such that head EH2 will be energizedduring the interval the length of the tape containing the portion of thePB signal recording which was clipped upon reproduction is passing erasehead EH2 or during the interval that portion of the picture signalrecording associated with signal CS is passing erase head EH2. Thus, themodified picture signal passed through circuit DCK will then be recordedon an erased section of the channel C2 in the exact position previouslyoccupied by the original gated section of the reproduced signal.

The apparatus of FIG. 6 may also be used to perform functions which arecommonly employed in still or motion picture photography, such as: (a)fading or blanking or erasure of a particular area or areas of a pictureor image field such as is commonly done in retouching a photograph, (b)fading or reducing the image intensity of an area or areas of the totalimage field being scanned and reproduced, (c) increasing the brightnessor amplifying the image field being scanned and reproduced, or (d)recording a second image signal over a particular area or areas of animage field.

In order to effect the last function, i.e., recording a new signal orsignals on a series of lengths of the recorded picture signal to effectthe production of a new image in said image field when said picturesignal is used to modulate the write beam of a video storage or picturetube, it will be necessary to obtain said new picture signal byreproducing it from a recording device.

FIG. 6 also shows means for effecting this action of recording a newpicture signal onto a particular length or lengths of the channel C2between the leading and trailing edges of the PB signal already recordedthereon. Said recording arrangement comprises a video storage tube SThaving an input W1 energizable for writing a video signal into thestorage element of said tube and a reading output R1 on which isgenerated a reproduction of the recorded video picture signal when atrigger pulse is received at read beam trigger input R2. The triggerinput to R2 may be derived from amplifier A3. If the storage element oftube ST is capable of producing a signal when scanned by its read beam,which, when recorded on member 10 of FIG. 6 as said recording member isdriven at the same speed in which PB was recorded, it will produce arecording having the same length as recording PB. Furthermore, if theimage area in the storage tube recording element is located along thesame coordinate of the storage tube, storage element as in the fieldscanned to generate the PB signals, signal segments for affecting saidimage area may be recorded onto the correct lengths of channel C2 asfollows:

The signal S1 is reproduced by a reproduction head PU1 as the leadingedge of picture signal PB first passes reproduction head PU2. Thereproduced signal passes to the trigger input R2 of storage tube ST. Theread beam of storage tube ST starts its sweep and the resulting outputsignal thereof is passed through a gate GT which is normally open and isclosed when a signal is present at its switching input that is connectedto amplifier A3. A delay line DT is provided between amplifier A2 andgate GT to account for the time required for triggering the read beam.It is assumed that the S1 signal is provided in a position to permit thereproduction of signal S1 to trigger storage tube ST to provide anoutput signal therefrom at the instant the leading edge of signal PBpasses head PU2. This lag, if any, can be also accounted for in delayline DT' which is connected between gate GT and the recording amplifierRA2 for recording head RH2. The recording amplifier RA2 is positionedwhere stage RA-CK is connected to delay line DT' and recording headRH-2. The time delay constant of delay DT' is such as to delay thepassage of the signal from storage tube ST a sufficient time to permitthe member 10 to travel the distance between heads PU2 and RH2. The gateGT is utilized to blank out all parts of the signal transmitted fromstorage tube ST except those of equivalent length and reproduced whenthe signals CS on channel C3 are reproduced.

In FIG. 7, a series of gating signals SC1, SC2, SC3 . . . SCN areprovided on channel C3 of magnetic recording member 10 adjacent a videopicture signal PB, which, as in the other hereinabove describedexamples, may comprise a composite video signal with picture, blanking,horizontal, and vertical sync pulses provided therewith. Each of said SCsignals are of a particular length and are recorded spaced apart inpositions relative to said PB signal. The SC signals may be used, whenreproduced simultaneously therefrom with said PB signal, to gateparticular or predetermined lengths of said PB signal which lengths weregenerated when a video scanning camera beam scanned across a particulararea or boundary in the image field being investigated.

An object or surface may be prepositioned in the field being scannedsuch that a point or points on the surface of the object are atpredetermined coordinate positions in the scanned image field. Then, aparticular area or areas, determined by said multiple gating signals SC,may be investigated to determine if smaller areas, spots, lines or thelike of different light characteristic than the background of saidselected areas exist therein. For example, surface defects such asscratches, marks, holes, discoloration and the like which appear asimages of different light characteristic than the general surface due toshadows, change of reflectivity or greater absorption of light, willcause a variation in the amplitude or frequency of the video picturesignal when said surface is scanned.

If PB signal is composite video signal recorded on channel C2 or ifother areas of the field being scanned are of equal or greater lightvariation than the surface defects or image phenomena beinginvestigated, the gating signals SC may be reproduced and employed. Inthis manner, such phenomena will not serve to confuse the functions ofmeasuring, counting or of otherwise determining the existence of orextent of such defects because said SC signals may be used to gate onlysections of the picture signal PB generated while scanning the area ofthe image field in which said defects or phenomena to be measured occursto the exclusion of other areas of said image field.

In FIG. 7, the SC signals are reproduced by head PU3 and passed to oneinput of a logical AND switching circuit AN23. The picture signalrecording PB is reproduced by magnetic reproducing head PU2 and passedthrough a reproduction amplifier A2 to a clipping circuit CC12. Theoutput of CC12 extends to the other input of circuit AN23. The clippingcircuit CC12 is adjusted in clipping level to detect the image phenomenaor surface defects in the area determined and gated by the SC signalsfor investigation. Whenever both signals from clipper C12 and amplifierA3 are present at circuit AN23 an output signal is produced therefrom.

Said output signal may be utilized in one of a number of manners. Thepresence of such an output signal may indicate a defect or undesirablecharacteristic of the surface being scanned and may be used to energizea relay which may effect one or more of such functions as the ringing ofa bell, energizing of other types of alarms, the stopping or starting ofa servo motor, actuation of a solenoid for rejecting or transferring thepart being scanned, or the pulsing of a counter. It may also bedesirable to count the pulses passed from AND circuit AN23 in a countersuch as counter TC which may contain circuit means for emitting a pulsetherefrom for control purposes of a predetermined count is exceededduring the passage of the entire PB signal. Notation AM refers to analarm triggered by an output from counter TC.

FIG. 8 is a schematic diagram illustrating signal recordings andreproduction means including control circuits for automatic dimensionalmeasurement. Means are provided for automatically and rapidlydetermining if a dimension in an image field, such as the distancebetween two surfaces, which dimension is discernible by variations orinflections in the light or color of the image defined at the limits ofthe investigated dimension, is positioned in a particular orpredetermined area therein and is of the same length as a standard orcomparative dimension. Said comparative dimension may be the length ofor distance across a similar component or area conforming to a givendimensional standard such as across an article of manufacture which isdimensionally acceptable and conforms to precise dimensionalmeasurements according to, for example, an engineering specification.

Measurement and position of the dimension or dimensions being inspectedand compared is accomplished in FIG. 8 by use of a video picture signalderived by video camera beam scanning the surface of the object or areabeing measured or compared. The said picture signal PB may be recordedor otherwise provided whereby it may be passed to a measuring circuit orcircuits at a time whereby the generation of said signal is synchronizedto the reproduction of other gating and position indicating signalsrecorded o a magnetic recording member.

In the hereinabove described video measuring and control techniques, oneor more video picture signals are recorded on a magnetic recordingmember in a precise position relative to one or more control or gatingsignals so that said other signals may be reproduced to gate particularlengths of the video signal and to indicate the position of particularpoints or areas in said video signal. The same results may be attainedby recording the video picture signal on any other medium such as thesurface of a storage tube provided that it can be reproduced therefromin a manner whereby it is synchronized in time to the generation of saidother signals. This may be accomplished in the arrangement of FIG. 1,for example, by reproducing the frame indicating or sync signal S1 andemploying said signal to trigger the sweep of the `read beam` of astorage tube. Said video picture signal is thereby provided on an outputcircuit at the same instant that it will be reproduced from a recordingon a magnetic recording member adjacent the other signals as described.

Similarly, the picture signals of the other figures including FIG. 8,may be recorded on other than the illustrated magnetic recordingmembers. Said video storage tube may also be replaced by a deflectioncontrolled camera scanning the image field being investigated such thatthe video scanning beam is triggered to effect a controlled scan by thesignal reproduction of the sync signal recording S on track C1. In FIG.8, the article or surface being investigated is located relative to thevideo scanner such that the image presented to the optical system ofsaid scanning apparatus is of a predetermined scale and is aligned insaid scanning field in a predetermined position so that comparison canbe made by the reproduction of said prerecorded multiple gating andswitching signals at predetermined intervals during the reproduction ofsaid video picture signal.

In FIG. 8, multiple signals are shown recorded on magnetic recordingmember 10 including a sync signal S1 for locating a video picture signalPB which is recorded adjacent signal S1 on a second track C2. A thirdand fourth signal CS3 and CS4 are recorded on tracks C3 and C4,respectively. For measurement of a particular length or distance in thevideo image field, the signals on track C4 comprise two signals CS4-1and CS4-2 which represent the end limits of the dimension or lengthbeing measured. Signal CS4-1, for example, is positioned relative to thePB signal such that it will be reproduced therewith and with anassociated length of said PB signal which is generated when the videocamera scanning beam crosses that part of the acceptable or standardimage in the scanning field which is located at one end of the dimensionbeing compared.

Referring now to FIG. 8' to illustrate the significance of the spacing,positions and lengths of the gating signals of FIG. 8, in FIG. 8' thereis provided a rectangular image field BF which is scanned on a rastertype scan by the video camera scanning beam. In said image field BF,multiple black or dark areas denoted A-A, A-B, A-C are located on abright or white background B-B such that each of said areas or patcheswill effect a variation in amplitude in the video picture signal whenscanned.

In order to discriminate between the different areas of similar ornearly the same light intensity, a signal CS3 is provided on channel C3to gate only that part of the video signal which is produced when thebeam scans or a particular portion thereof which is the particular areato be investigated or measured. Recorded signal CS3 has a length L whichis derived during scanning the distance L illustrated in FIG. 8'. Thedistance L extends across the rectangular area A-C and includes a briefdistance either side of A-C but not so far as to possibly overlap theother areas A-A and A-B. The area A-C is shown as rectangular and havingside borders which are parallel to the borders of the total image fieldBF. The dimension L will be determined by the degree that the patch areaA-C may shift in position from one sample of area being inspected to thenext and the closeness of an adjacent area such as A-B which would causea similar variation or inflection in the video signal generated duringscanning A-C which would cause an incorrect measurement or preventmeasurement.

The dimension D represents the width or length of that part of anacceptable or standard area A-C which is crossed or scanned by the videocamera sweep beam. In FIG. 8', dimensions D represents the required orspecified width of area A-C and is shown in FIG. 8 as a distance betweencenterlines drawn through signal CS4-1 and signal CS4-2. The toleranceor accepted degree that the leading edge El of the are A-C may beshifted from its specified position may be indicated by the length ofthe signal CS4-1. The acceptable degree that the trailing edge E1 ofarea A-c may vary from its specified position may be indicated by thelength of the signal CS4-2. Thus the distance between the centerline ofsignal CS4-1 and the leading edge of signal CS4-1 may be considered aplus tolerance and the distance from said centerline to the trailingedge of signal CS4-1 may be considered a minus tolerance as defined inconventional measurement practice. These dimensions are respectivelyreferred to in FIGS. 8 and 8' by the notations +T and -T.

The length of signal CS4-1 is equivalent to 2T having a dimension orlength determined by the speed at which the picture signal generatingbeam is scanning the image field BF and the acceptable variation of saidarea from a desired or specified point or line in the image field. Ifthe area A-C has within its borders image characteristics which wouldinterfered with the comparison-measurement function, the gating signalCS-3 may be provided as two or more signals falling sufficiently on bothsides of the centerlines of the CS4-N signals to permit the comparativemeasurement to be effected.

In FIG. 8, reproduction heads PU1 to PU4 pass signals from theirrespective channels to respective reproduction amplifiers A-1 to A-4 asmember 10 moves relative thereto. The reproduction of the PB signal ispassed to a clipping circuit CL2 and is adjusted in clipping amplitudeor level to produce a signal output therefrom when the increase ordecrease in amplitude caused by the sweep of the camera beam in movingacross the edge of area A-C appears in the reproduced signal PB. Theappearance of this signal at clipper CL2 thus indicates the position ofthe leading edge of the image area A-C being compared. The reproductionof signal CS3 is passed to the switching input of a normally open,monostable gate or switch G2 to maintain said gate closed and complete acircuit while said reproduction of signal CS3 is passed therethrough.

The output of clipper CL2 is passed to a Schmitt circuit CM which is acathode coupled multivibrator having an inverter at the output of themultivibrator. Said Schmitt circuit will produce a short pulse outputeach time a signal at its input inflects a predetermined degree inamplitude. For example, if an elongated pulse is passed to Schmittcircuit CM, the leading edge of said pulse will cause a short pulse tobe produced at the output of Schmitt circuit C and the trailing edge ofsaid pulse will cause a second short pulse to be produced at saidoutput. Thus, if the clipping circuit CL2 produces a signal of a givenduration generated as that part of the reproduced PB signal which wasproduced as the scanning beam scanned across an area such as A-C in theimage field of a different light intensity or color than the surroundingfield, the distance across said area along a specific scanning line ofthe scanning path STL may be determined by measuring the length of saidsignal or the distance between the two points where said picture signalPB changes in amplitude.

If the area A-C provides, when so scanned, an increase or positiveinflection in the picture signal, then clipping circuit CL2 will producean output signal whenever its input is energized by that part of thepicture signal generated when the beam crosses from the border to borderof area A-C. The Schmitt circuit CM will produce short pulses when theleading and trailing edges of the signals from clipping circuit CL2arrive thereat. The gating signal CS3 will determine which of the sweepsacross area A-C will be used for measurement and will prevent thepassage of signals produced by Schmitt circuit CM as the result ofscanning the other areas A-A and A-B in the field BF.

The output of Schmitt circuit CM is passed to one input of a logical ANDcircuit AN2-4. The other input of AN2-4 is connected to the output ofamplifier A4. The output of Schmitt circuit CM is also passed through adelay line D2 to the input of a logical NOT circuit N2. The switchinginput of circuit N2 is connected to the output of the AND circuit AN2-4.Delay D2 is provided to account for the switching time of circuit AN2-4so that, if a pulse is produced at the output of Schmitt circuit CM atthe same time that CS4 is being reproduced, it will not pass through theNOT circuit N2 but will be stopped by the appearance of a pulsegenerated by AND circuit AN2-4. When there is no output from NOT circuitN2, the leading edge and/or trailing edge of area A-C fall within thearea or position indicated by signals CS4-1 and CS4-2. If the pulseshould be produced from Schmitt circuit CM when there is no signaloutput from amplifier A4, the AND circuit AN2-4 will not produce anoutput and said pulse will pass through the NOT circuit N2.

The output of NOT circuit N2 may be connected to one of more of a numberof electrical devices such as a relay or recording head. The relay REmay be used to activate a warning signal generating device, stop amachine, effect a visual or magnetic recording, send a signal to acomputer, etc.

A simplification of the recording arrangement and apparatus of FIG. 8involves the elimination of the signal CS3, its reproduction apparatusand the gate G2. However, the channel C4 must be noise free and cannotcontain other signals which would give a false indication of thecondition of the PB signal. If the recording member 10 is a magneticdrum or closed loop tape, it may be rotated or travelled at constantspeed and may be used to repeat the described comparative measurement byeither intermittently recording and erasing a PB signal of thephenomenon being measured from member 10 or providing said positionindicating signals CS at time intervals and synchronized to thegeneration of a video picture signal generated in scanning saidphenomenon. The signal S1 on channel C1 may be used to trigger the sweepof a video camera scanning device to start producing said picture signalat a predetermined instant when a particular length of the recordingmember 10 is passing the reproduction heads or is in a predeterminedposition relative to said heads, during its travel, so that the similareffect will be attained as obtained in recording said signal on aspecified length of said member 10 relative to said other signals andsimultaneously reproducing said signals therefrom.

FIG. 9 illustrates means for automatically measuring a distance ordistances between points in a video image field such as the distancebetween two coordinates where a scanning line STL crosses the borders ofa particular area in said field or the borders of two predetermined orspecified areas. An example of such measurement is the rectangular imagefield BF having an area or patch A-C as shown in FIG. 8'. The area A-Cis characterized by a different radiation or light intensity than itssurrounding field area BF. To simplify the description, the sides orborders of area A-C are parallel to the borders of the field BF. Thewidth D of area A-C may be automatically determined by automaticallymeasuring the length of that part of the picture signal produced duringscanning the width of said area, or, assuming that scanning speed isconstant, determining the time it takes for the beam to travel from oneborder to the other. If it is known how long it takes for the scanningbeam to travel a unit distance across the area or surface AC, then thewidth or any predetermined dimension of area A-C may be measured bytiming the interval it takes for points in or portions of the picturesignal generated by such scanning to each exist in or arrive at ameasuring circuit.

Provided that the area A-C is of a known and predetermined scale in BF,the actual distance D is obtained by multiplying the time it takes forsaid beam to sweep across said area by the proper time constant. Thelatter may be derived if the speed of scanning is known and the time ittakes for the scanning beam to sweep or travel a unit distance isdetermined. Assume the picture signal generated in scanning the field isrecorded on a magnetic recording member 10, as shown in FIG. 9, whilesaid member is driven at constant speed. Then, distance D may bedetermined by accounting for the speed of said tape, the time intervalbetween the reproduction of that segment of the PB signal generated whenthe scanning beam crosses the border E1 of area A-C during a single lineand the reproduction of that segment of PB generated when said beamcrosses the border E2.

FIG. 9 shows means for effecting a measurement whereby the picturesignal PB derived by scanning field BF is recorded in a predeterminedposition on a magnetic recording member 10 relative to multiple gatingsignals CS3 recorded at predetermined positions on channel C3 and signalCS4 recorded on channel C4. Signal PB need not be so recorded if it maybe generated in a measuring circuit such as that illustrated in FIG. 9at a predetermined time relative to the generation of the otherillustrated signals.

Whereas in FIG. 8 the length of a short pulse signal on channel C4determined a tolerance range for the position of a line or border imagein the field, in FIG. 9 such a positional tolerance is determined by thepositions of the respective leading edges of signal recordings CS3-1 andCS4-1. This is effected by passing the output of reproduction amplifierA3, which output is the reproduction of recorded signal CS3-1, to aninput of a dual input AND circuit AN23 and the output of reproductionamplifier A4 to the switching input of a normally closed monostable gateor NOT switch N2 which is switched to open when a reproduction of theCS3-1 signal is present thereat.

Thus, if there is an input to NOT circuit N2 resulting from apredetermined change or characteristic of signal PB being clipped invideo clipper CL-2, there will only be an output from AND circuit AN23if signal CS3-1 is being reproduced but not CS4-1. The positions of theleading and trailing edges of signals CS3-1 and CS4-1 thus determine thetolerance range of the position of the border of the area or otheroptical line phenomenon being measured.

Signal CS3-1 of FIG. 9 has the length equivalent of L in FIG. 8' andsignal CS4-1 has the length equivalent to L minus 4T where T is thedistance in the field BF along which field the border of area A-C mayshift either side of a normal or standard position without fallingoutside of a desired tolerance range.

The signal CS4-1 of FIG. 9 has the effect to blank and preventtransmission to AN23 of any signal which may be reproduced when aportion thereof falls beyond the limits of the inside tolerance limits.Thus any images situated within area A-C which would confuse or preventmeasurement are eliminated from said measurement. If area A-C has areaswithin its borders similar in intensity to field BF, signal CS4 may beso positioned on a recording member and has a length sufficient toprevent the passage of any signal from the clipping circuit which willproduce an output and interrupt the signal passed therethrough whilesignal CS3 is present thereby to produce variations or multiple pulsesin the output of AND circuit AN23 which will switch the flip-flop FC.

For example, the area across which it is desired to effect a linealmeasurement may not be an area having changes or interruptions (such asLA') in the composition of the image pattern within its borders whichwill cause variations in the picture signal which will confuse orprevent measurement. To effect dimensional measurement by scanning, itis necessary to block any output from Schmitt circuit CM to themeasurement apparatus illustrated which is not a pulse generated bysignals produced at the leading edge and trailing edge of the border ofthe area being scanned for dimensional measurement. The position ofsignal CS4 is such that, when reproduced and passed to a logical NOTcircuit, it will prevent the output signal from Schmitt circuit CMproduced during the same time interval as signal CS4 is generated frompassing to the AND circuit AN23. This is effected by connecting theoutput of amplifier A4 to pass the reproduction of the CS4 signal orsignals to the switching input of NOT circuit N2 thereby disconnectingor breaking the circuit between circuit CM and AND circuit AN23.

Also illustrated in FIG. 9 are means for automatically adjusting certainof the circuit variables such as the clipping level of the clipper CL2.This may be effected automatically without adjustment by the provisionof one or more signals recorded on said recording member in positions tobe reproduced to effect the desired adjustment by controlling a servomotor coupled for providing said adjustment.

FIGS. 9 to 12 illustrate means for automatically adjusting the clippinglevel of clipper CL2 one or a number of times during said automaticmeasurement cycle. Means are also provided for effecting the selectionof one of multiple of outputs K1 to KN over which to gate the results ofmeasurement. A number of other functions may also be automaticallyadjusted by reproducing prerecorded signals from member 10. For example,the degree of amplification or attenuation of all or part of the picturesignal may be adjusted by recording one or more signals on channels C5to CN of the member 10 in positions to be reproduced and effect therequired adjustment or control prior to or during a measurement cycle.

If recording member 10 is driven at constant speed, the duration of asignal recorded on and reproduced therefrom prior to or during thereproduction of the picture signal may be employed to drive a servomotor from a zero set condition for a predetermined time to position theshaft of a variable resistor, capacitator or inductance a predeterminedadjustment. A series of equispaced, equi-duration pulses reproduced froma single auxiliary channel may also be passed to a solenoid for steppinga switch to a selected position to select one of a plurality of outputcircuits on which to transmit.

The results of measurement digital code recorded either in series or inparallel on a multiple of said auxiliary channels may be passed to thedigital-to-analog converter or shaft positioner which is adapted toadjust a variable potentiometer or rotary switch. In FIG. 9 servo motorSM is coupled through gears GR to the shaft of a variable potentiometerR9 in the grid-cathode circuit of the clipper CL2 to effect apredetermined adjustment of the potentiometer shaft by means of a signalreproduced from C8. The motor SM is controlled by forward and reversecontrols F and R which are energized by signals reproduced from channelsC8 and C7. Thus, if member 10 is driven at a predetermined and constantspeed past the reproduction heads, the length of a signal recorded onsaid member will be equal to a specific time said signal exists in theoutput of the respective reproduction amplifiers.

A signal of a particular duration recorded on channel C8 will maintainthe control F of motor SM energized for a particular time whereby theshaft of the servo motor SM will be driven a predetermined number ofrotations which is used to preset or to predetermine the clipping levelof clipper CL2. This may be effected by controlling said motor topositionally control the shaft of the potentiometer Rg in one directionby signals reproduced from channel C7 of member 10 and in the otherdirection by signals reproduced from channel C8 by the reproductionamplifier A8. Amplifier A8 is operatively connected to the forward drivecontrol F of servo SM as shown in FIG. 11 to preset the shaft of thevariable potentiometer Rg in the grid-cathode circuit of the triode tube6J5 of the clipper CL2 as illustrated in FIG. 10.

A signal recorded on channel C7 may be of such a length to reset theshaft of potentiometer Rg to zero as shown in FIG. 11. Subsequently, asignal reproduced from channel C8 is fed to the forward drive control Fof motor SM to preposition said shaft, thereby adjusting thepotentiometer operated bi-stable solenoid actuated switch adapted toeffect the reversal of motor SM. The motor SM continues its reversetravel until the shaft of the potentiometer Rg has reached a zeroposition.

In FIG. 11, a limit switch LSW is shown adjacent a zero stop pin SMS.When actuated by the brush arm BA of the variable potentiometer Rg, stoppin SMS is adapted to stop motor SM at a reset shaft position. Forconventional video apparatus variable potentiometer Rg has a range of5000,000 ohms to 3 megohms permitting any predetermined level of videoamplitude in the picture signal range to be clipped according to thesetting of said shaft RPS.

A second method of presetting the potentiometer Rg is to record one ormore digital codes on one or more channels of member 10. These digitalcodes are then reproduced at a particular instant during thereproduction of the picture signal recording PB or prior thereto andused to effect the angular positioning of said shaft. FIG. 10illustrates apparatus for effecting such shaft positioning by means of adigital-to-analog converter DAC. The input to converter DAC may be aseries or parallel digital code reproduced from recordings on the member10. The digital to analog converter consists of a setting unit DAC" anda control unit DAC' for receipt of said digital input from amplifier A5.The setting unit DAC" positions the shaft to the number of revolutionsand fractions of a revolution determined by the coded signal inputreproduced from recording member 10. The output shaft of setting unitDAC" is coupled by gear means GR to the shaft of the variable resistor.The setting of the resistor Rg determines the clipping-level of clipperCL2.

Also illustrated in FIG. 9 are means for automatically selecting one ormore circuits over which to gate information derived from the measuringoperation described. The output of pulse counter CT is connected to theinput of a multi-output selection switch MS which is a rotary steppingswitch that is capable of attaining one of a particular number ofswitching positions as predetermined by pulse signals provided at aninput ST thereto. A signal to a resetting input RST resets said switchto a zero switching position.

The output of counter CT may be a digital pulse or pulse trainindication of the count and may be passed to one of a number ofcomputing, recording or control circuits for effecting or performingvarious computing, recording or control functions. In FIGS. 9 and 12,means are shown for automatically gating the output of counter CT to oneof multiple circuits K1 to KN. Signals recorded on recording member 10are used to select which of the circuits K1 to KN the output of counterCT will pass to.

This means may also be employed to gate segments of the picture signalFB to one of a plurality of different circuits or to gate the output ofany of the other illustrated devices such as clipper CL2 or Schmittcircuit CM to one of multiple circuits for recording, measurement orcomputing purposes. A multiple circuit rotary switch MS has its inputconnected to counter CT.

In FIG. 12, switch MS comprises the combination of solenoid SOLoperative, when its input is pulsed, to actuate a ratchet and pawlmechanism RP which steps a shaft RPS to move a potentiometer electricalwiper arm WA to the next switching position. The input to solenoid SOLis derived from the reproduction amplifier A5. If shaft RPS is reset toa zero position, the number of pulses recorded on channel C6 willdetermine the position to which shaft RPS is moved. Hence, the switchingof the input to the selected output circuit is effected. A servo motorSM' actuated by a signal reproduced from channel A6 may be used to resetor drive the shaft RPS to a zero position at the end of the measuringcycle. The electro-mechanical switching means of FIG. 12 may be replacedby an electronic device such as a magnetron beam switching tube with theinput from A5 connected thereto for switching said beam one switchingposition each time a reproduced pulse is received thereby.

The hereinabove described means for effecting automatic switching mayalso be used to gate a selected of a plurality of signals or voltages toone or more selected circuit adapted to effect measurement of the typedescribed prior to or during the reproduction of the picture signal.

The recording arrangement and measuring apparatus of FIG. 9 is subjectto a degree of variation without departing from spirit of the inventionas related to automatic dimension positional measurement. For example,the pulses produced at the output of the respective Schmitt cathodecoupled multivibrator circuit CM by the leading edges of the reproducedcontrol or gating signals CS3 and CS4 may be used to define ameasurement or tolerance range along a scanning line in the field beingscanned. If amplifier A3 is connected to a Schmitt circuit CM, it toowill produce a pulse when the leading edge of signal CS4 appears. Thefirst pulse produced by the leading edge of signal CS3 may be used tostart a digital timer of the type described and the second mentionedpulse to reset said timer. A pulse or pulses produced by clipping andpassing the picture signal PB through a Schmitt circuit CM may be usedto effect a binary digital code output from said timer which isindicative of the location of said change in said picture signal betweenthe leading edges of signals CS3 and CS4. The leading and trailing edgesof the CS3 and CS4 signals may thus define the limits of a dimension orpositional tolerance range.

The pulse counter CT may also be replaced by a digital timer or clockDIT of the type hereinabove illustrated and used. A timer DIT indicatesby a digital output therefrom where said change occurs in said picturesignal relative to said CS signals or to the beginning of said picturesignal. In the latter example, the digital timer DIT may be started bythe reproduced signal S1, the first pulse output of AND circuit AN23 oranother signal recorded on and reproduced from channel C1 or on anyother channel which signal is positioned in a predetermined location ofa tolerance range for the particular image phenomena being measure.

An apparatus for automatically scanning work-in-process and fordetermining by one of the means hereinabove described is shown in FIG.13. The following phenomena may be determined:

(a) If the contour or shape of a work-piece conforms to a given contouror falls within specified dimensional limits of a given contour,

(b) If a particular or predetermined part or dimension of saidwork-piece conforms to a predetermined dimension and/or is positionedrelative to other parts or areas of said work-piece within givendimensional limits,

(c) If predetermined image areas exist or do not exist on said work suchas production markings, components assembled therewith, imperfections,components or material, etc.,

(d) The actual measurement of a predetermined or specified dimensionacross said work or across part of said work, and

(e) Other of the numerous functions commonly performed by visual ormanual means or mechanical measuring devices in inspecting or measuringwork in process or finished goods.

FIG. 13 shows a means for conveying a series of article of manufacturepast a scanning station SC-ST. The conveying means comprises a conveyorCV illustrated as an endless motor driven belt but which may be anyknown type of article conveyance. For the purpose of simplifying thedescription, the workpiece or article W to be scanned is shown as anoblong block or box-shaped solid with a series of steps formed therein.Any dimension across the article such as the illustrated d1 and d2dimensions extending across the first two steps in the upper face ofworkpiece may be automatically determined by the means provided in FIGS.9 to 12.

During inspection scanning, the work is held stationary by an automaticclamping fixture. However, scanning may be effected on-the-fly uponphotoelectric detection thereof on the conveyor, preferably while in apredetermined location and aligned in the scanning field to provideaccurate measurement. The positions of said step-like formationsrelative to one end W1' of workpiece may be automatically determined bythe means of FIG. 4, or relative to the position of an area such as areaW1 which may comprise a hole, formation on said part or componentassembled therewith determined by the means of FIG. 8. The recordingmember 10 illustrated in FIG. 14 comprises a closed loop tape which iscontinuously driven in a fixed path at a constant speed for effectingsaid recording and reproduction relative thereto by magnetic transducingheads RH and PU.

At a scanning station SC-ST, a video camera CAM is fixed on a mountrelative to the conveyor CV and is focused to scan the surface WS whichfaces the camera when workpiece W is aligned at a predetermined positionon conveyor CV and the front end WE is at a predetermined position inthe longitudinal travel of the conveyor CV. Simple means are provided inFIG. 14 for aligning the work W relative to the scanning camera CAM.However, more complex alignment means or fixtures may be neededdepending on the shape of the work, the characteristics of the scanningdevice CAM and its optical system, and the precision required for theautomatic measurement.

The work W travels in the attitude illustrated in FIGS. 13 and 14 alongthe conveyor CV prior to reaching scanning station SC-ST. An alignmentbar AB extends over the conveyor CV. The work W is pushed against bar ABby a pusher bar B1 which is operated by an air or hydraulic cylinderCY1. The operation of cylinder CY1 is effected when the leading surfaceWE of the work has reached a predetermined point in its longitudinaltravel in the scanning field BF.

A photoelectric cell PH and photoelectric control PHC therefor areprovided. Control PHC transmits a pulse over an output circuit whenlight from a light source LS mounted across the conveyor is cut orinterrupted by the work W as it moves past. The interruption of thelight source LS initiates the action which prepositions workpiece W inthe scanning field. The transmitted pulse activates a control for an aircylinder CY2 which thereafter projects an arm B2 across the conveyor CV.The face WE comes to rest against arm B2 thereby aligning workpiece W inthe field when bar B1 is projected by cylinder CY1 to force face WSagainst alignment bar AB.

The workpiece W is thus essentially provided in a predetermined positionrelative to the scanning camera CAM with the surface WS to be scanned ata predetermined attitude relative to said camera scanning field Theoutput of control PHC is thus passed over two circuits. A first isconnected to a control F of cylinder CY2 which is one input of asolenoid actuated electro-mechanical flip-flop switch which opens avalve and actuates the cylinder CY2 projecting the bar B2. The pulse isalso passed to a time delay switch D2. A pulse is then transmitted fromswitch D2 to the forward control F of cylinder CY1.

The delay period of delay switch D2 is such that pusher bar B1 will beprojected against workpiece W a time interval thereafter which issufficient to permit the surface WE to engage and align itself againstbar B2. When workpiece W is so aligned, scanning of the field by scannercamera or flying spot scanner CAM may take place in such a shortinterval that bars B1 and B2 may be retracted within a fraction of asecond after bar B1 has urged workpiece W against bar AB. Therefore, theconveyor CV need not be stopped during this action.

Thus, cylinder CY1 is adapted to automatically retract at the end of itsforward stroke. The return travel of cylinder CY1 may be used to actuatea limit switch thereby completing a circuit with a solenoid which closesor opens a valve to activate cylinder CY2 retracting bar B2. This actionis accomplished in FIG. 14 by delay relays D2' and D2 which providepulses for energizing the reverse controls of the flip-flop switchescontrolling fluid actuated cylinders CY1 and CY2 for retraction thereofa short time after bar B1 urged workpiece W against bar AB.

The scanning action is accomplished as follows: The pulse signal outputof control PHC is also passed through delay line D1 to respective timedelay relays D3 and D4 and through line L1 as shown and to thecomplement input C of an electrical bi-stable unit or flip-flop switchFL2.

A first pulse transmitted through line L1 to switching control C offlip-flop switch FL2 switches the picture signal output of the videoscanning device CAM over a circuit to the writing or recording input RIof a video storage tube STT. The image signal derived from scanning thesurface of the prepositioned workpiece W is recorded on the storageelement of the storage tube STT as described below.

After being energized by the signal on the output of delay line D1,delay element D4 transmits a second pulse to switching control C offlip-flop FL2 a time delay period after transmission of said first pulseto effect the recording of the video picture signal on the storageelement of STT. Thereafter, flip-flop FL2 switches to a conditionwhereby the circuit between the scanner and the storage tube STT isbroken. Therefore, when the workpiece W starts moving again after bar B2retracts, the recording in storage tube STT will have been effected.

A delay relay D3 having a time constant equal to that of delay relay D4or greater permits the picture signal to be read into the storage tubeSTT before effecting the recording of said picture signal on themagnetic recording member 10 in one of the manners hereinabovedescribed. Said picture may otherwise be used as described to effect ameasurement or comparison by reproducing it simultaneously with signalsgenerated by reproduction from member 10 in the manners provided inFIGS. 1 to 12.

The output of delay relay D3 is passed to a flip-flop switching circuitFL2' which is a normally open switching means. Upon receipt of a pulsefrom delay relay D3, switching means FL2' closes for a predeterminedperiod of time after which it automatically opens. The input to switchFL2' is derived from reproduction amplifier A1. When the reproductionhead PU1 reproduces the sync signal S1 from channel C1 of recordingmember 10, said S1 pulse is passed to read trigger control RT of storagemeans STT. Control RT triggers the read beam control of said videostorage tube STT and causes said beam to sweep the surface of thestorage element and produce an output therefrom which is a video picturesignal. The output is passed to a recording amplifier RA2 and recordedon channel C2 through recording head RH2 in a fixed position relative tothe signal S1 recorded on channel C1.

The trigger control RT comprises a vacuum tube gate for changing thepotential of the read gun element (not shown) of STT to the desiredvoltage for effecting automatic reading of the stored signal. A powersupply PS is gated to control RT when control RT is actuated by thepulse from amplifier A1. The circuit between amplifier A1 and switch RTremains closed for a period to permit member 10 to travel at least onecycle. Therefore, regardless of where the recorded signal S1 is locatedwhen flip-flop FL2' is first energized, the reproduction of signal S1will pass through switch FL2' to switch RT before the switch RT opens.The output of flip-flop FL2' is also passed to a time delay switch FL3.Delay switch FL3 is in the circuit of the recording amplifier RA2 andthe recording head RH2 and maintains said circuit closed for a period oftime necessary to effect recording of at least one complete video framepicture signal onto member 10.

FIG. 15 is a schematic diagram showing a further means for producing afirst positive pulse when the leading edge of an elongated signal orpulse appears in a circuit and a second pulse output when the trailingedge of said signal appears thereat. The circuit of FIG. 15 may besubstituted for the Schmitt cathode coupled multivibrator circuit CM ofFIGS. 8 and 9.

The circuit of FIG. 15 includes a differentiating circuit DCT comprisinga capacitator and resistance of very small time constant, e.g., in theorder of 10⁻¹² microseconds. The input to the differentiating circuit isfrom the clipping circuit CL2 of FIGS. 8 or 9. A summing amplifier orintegrator SA is provided in the circuit with three inputs to its grid.One input to summing amplifier SA is derived directly from a crystaldiode CD1 of the differentiating circuit DCT. Another input to summingamplifier SA is from the output of a DC amplifier inverter IN. A secondcrystal diode CD2 is in the circuit of differentiating circuit DCT andinverter IN. A feedback loop is shown from the output of SA to itsinput. The Schmitt circuit summing amplifier CM of FIG. 15 will providea dual signal output, as described, when a prolonged signal passes toits input.

In FIG. 14, the output of the photoelectric detector PHC is connected tothe trigger input TC of the video scanner or camera CAM through a delayrelay or delay line D1' and switch. When energized, the trigger controlTC may be adapted to cause the camera CAM to effect a cycle of beamscanning of the image field including the workpiece being inspected.Then, the single frame video picture signal generated on the outputR-CAM may be passed directly to a recording member such as a magneticdrum or disc for direct recording thereof without employing theintermediate storage tube STT for storage. Synchronization of thereproduction of the video signal from the recording member 10 with thereproduction of a comparator video signal or gating signals as describedmay be effected by clipping the vertical sync signal from the compositepicture signal so recorded That is, said vertical sync signal is used tosynchronize the recording and/or reproduction of said comparator signalor signals.

The input RI extends to the modulation and deflection control circuitsfor the write-beam of the video storage tube STT. The input RI receivesthe video picture signal generated at the output R-CAM of the videocamera CAM.

When the trigger input for the reading control RT is pulsed by areproduction of the frame pulse signal S1, the stored video signal instorage tube STT is generated on output OST. In FIG. 14, the videocamera CAM contains a trigger control TC for full frame scanning. Referto my U.S. Pat. Nos. 3,646,258 and 3,051,777 for greater details offrame trigger control TC.

In FIG. 1C, the output of AND circuit AN4N may be used for variouscontrol or computing purposes. If the motion of member 10 is coupled orsynchronized to the motion of a machine tool carriage or component, thesignal from AND circuit AN4N indicates that the condition preset in theRN switches has been attained and the output from AND circuit AN4N maybe used to start or stop a servo device driving said machine orassociated therewith. It may be desired to open or close a valve,actuate a solenoid, reverse direction of a driving motor, etc. when saidcondition has been reached.

The relay RE of FIG. 10 may be used as a gate to perform any of thegating functions described in this invention and may be used whenenergized by an output from AND circuit AN4N to effect one of varioustransducing actions on the generated or recorded picture signal; namely,

(a) An output from AND circuit AN4N may indicate that a desired point inthe length of the magnetic recording member 10 has been reached (i.e.one containing a specific picture signal recording of a multiplicity ofdifferent picture signal recordings). Said output may be used to effectreproduction of said picture signal from the recording thereof bycompleting a circuit between the output of the respective reproductionhead PU2 or amplifier A2 and another output circuit connected, forexample, to a recorder, etc. Actuating the relays R4 to RN in apredetermined order may thus be used for selectively reproducing picturesignals from member 10. The unit length U of the code may extend thelength of a specific signal recorded adjacent thereto that the outputgate will be open at the time said signal recording is present at therespective reproduction head.

(b) Similarly, an output from AND circuit AN4N may be used to erase aspecific signal or length of a signal recorded on member 10.

(c) If bit information is recorded on channels C1 and C2 and any otherchannels necessary to effect numerical recording for digital computing,control or storage of information, the preselection coding means of FIG.10 may be used for selecting from a specific channel or channels thereofa signal or signals in code form which may be present on a known lengthof said member or tape 10.

FIG. 16 illustrates an inspection station, preferably along a productionline, which is more versatile than the apparatus illustrated in FIG. 14.Means are provided for relatively moving both a beam scanning device andwork to be inspected whereby different areas of said work are presentedto the scanning field of the scanning device. The scanning device CAMmay comprise a deflection control beam scanning video camera, asdescribed, or any suitable radiation scanning means such as oneutilizing X-rays, infra-red radiation received from the article beinginspected, sonic or other forms of radiation detection and scanningmeans.

The scanner CAM is mounted on a manipulation apparatus 61 having one ormore arms which are supported from above. For details of a typicalarticle manipulator and the automatic control thereof to cause anarticle such as the scanning camera CAM to travel a predetermined pathin the realm of its motion, reference is made to my application Ser. No.477,467 filed on Dec. 24, 1954, and other copending applications whichrefer to computer controlled or programmed manipulators. The manipulator61 has a first vertical arm 62 which is rotatable and defines a joint62J for supporting a second arm 63. At the end of arm 63, the scannercamera CAM is supported on a base 65 which is preferably power pivotableand/or rotatable by means of servo motors mounted within the arms 63and/or base 65.

Scanning of the field immediately in front of the optical system of thescanner CAM may be effected while said scanner is stationary afterhaving been automatically prepositioned by means of a programmingapparatus or computer and/or while it is in motion as defined bymovement of the manipulator 61. The output of the scanner CAM comprisesone or more frame picture signals and is passed to a recording apparatusof the type described. The output is recorded or immediately comparedwith a standard picture signal or signals to determine variations inportions of the image field as hereinabove described.

The apparatus illustrated in FIG. 16 comprises an inflow conveyor 50illustrated as a closed loop belt or flight conveyor. A plurality ofslide bars 51 constituting guide means are mounted above the conveyor 50to define the alignment of articles delivered along a central portion ofconveyor 50. Therefore, said articles will be carried onto a turntable54 having means for prepositioning and clampingly engaging the lowerportion of the article. The surface of the article is thereby alignedrelative to the optical scanning field of the scanner CAM.

The turntable 54 is shown pivotally mounted on a base 56. Turntable 54is pivotable to effect discharge of articles thereon onto a receivingconveyor 52 after scanning has been effected and to rotate the articleabout a yaw axis relative to the scanner. Therefore, different portionsof its surface may be presented in the scanning field thereof while thescanner is held stationary or moved in a predetermined manner. Theturntable 54 is also rotatable about its central axis by means of amotor 54M which is operatively coupled to frictionally or otherwiseengage a surface of the table and rotate it as the motor 54M isoperated. Thus, the work held against the surface of the turntable 54 ismovable about the central axis of the turntable so that a further degreeof movement of the work is attained. The turntable 54 may also bemovable about a third axis which is parallel to the direction of theconveyors 50 and 52 so that the work may be rolled, pitched and yawed inaccordance with control signals derived from a computer or a programmingmeans. Consequently, substantially most of the surface of the work maybe presented in the scanning field of the electro-optical scanning meansCAM.

Side clamps 58 and 59 are movable by respective servos 58M and 59M toengage opposite surfaces of the work after it has been discharged ontothe upper surface of the turntable 54. A clamp or stop 60 is projectibleupwardly through an opening in the turntable 54 to limit the forwardmotion of the base of the work and preposition said work prior tooperation of the side clamps 58 and 59 thereagainst. Clamp or stopmember 60 is preferably retractable into the turntable 54 at the end ofthe inspection cycle. Thus, the work on the turntable may be released byforwardly tilting said turntable 54 after the clamps 58 and 59 have beenretracted. Such action will result in discharging the workpiece justinspected onto the receiving conveyor 52 whereby it is carried to thenext work station.

All of the described servos and actuators for the turntable 54, theconveyor motors and the motors powering the camera manipulator may becomputer or program controlled to effect prepositioning of the workrelative to the scanner and presentation of predetermined portions ofthe surface of the work in the scanning field.

FIG. 17 illustrates article positioning control means applicable to theapparatus of FIG. 16. However, positional control means for the scanneris not shown. It is assumed that it may be provided in accordance withthe teachings of my copending application, Ser. No. 477,467 andinterlocked with the detection of an article at the inspection station.

The article is detected upon arriving at the turntable or inspectionstation by means of a photoelectric cell and control PHC which generatesan output pulse. Said output pulse is passed to both the forward startcontrol F of the tape transport drive motor MT and a trigger input 32aof a multi-circuit timer or controller 32. Controller 32 has pluraloutputs for controlling the projection and retraction of the servos 58M,59M and 60M for clampingly engaging said workpiece and prepositioning itat the inspection such as on the turntable 54 of FIG. 18.

The controller 32 also provides a signal to close a normally open switch33 disposed in the output of magnetic tape reproduction transducer PU1and the trigger input TC for the deflection control chain of the scannercamera CAM. Consequently, when the frame indicating pulse S1 recorded onthe channel C1 of the magnetic recording member 10 is reproduced, itwill pass to the trigger input TC of the camera to effect deflectioncontrol of its scanning beam in a single frame sweep of its image fieldwhich includes at least a portion of the surface of the workpiece.

The picture signal modulated on the output RCAM of the scanner is passedthrough a flip-flop switch 34 to one of two recording heads RH3 or RH4depending on the condition of flip-flop 34 and is recorded onto eitherchannel C3 or C4 of the tape 10. The other channel contains either thepicture signal derived in scanning a standard image field, portions ofwhich standard image field are to be compared with portions of the fieldbeing inspected, or scanning the previous article or field forcomparative scanning analysis. In other words, the apparatus illustratedin FIG. 17 may also be used for the continuous surveillance of a floorarea, landscape or other form of display attained, for example, fromscanning a particular area, volume or continuous flow of materialprovided that the cycle controller or timer 32 is utilized only to timethe scanning of the camera and not to control the operation of articleprepositioning and clamping means.

Accordingly, the flip-flop switch 34 will be generally applied where itis desired to effect automatic comparison of portions of one picturesignal with similar portions of the previously generated picture signal.Switch 34 may be bypassed by directly connecting the picture signaloutput of camera CAM with one of the two recording heads RH3 or RH4.Means may be provided for automatically erasing the previously recordedpicture signal on the channel to receive the new recording or forimmediately comparing the just-generated picture signal with a standardpicture signal recorded on tape 10 in a signal analyzer 30 of the typehereinabove described. The signal analyzer 30 of FIG. 17 is illustratedas operatively coupled for receiving the two picture signals recorded onchannels C3 and C4 as well as gating signals SC recorded on channel C2to effect the automatic measurement functions hereabove provided.

The flip-flop switch 34 may be operated to switch the picture signaloutput of camera CAM alternately from one channel to the other by theframe position-indicating-signal on channel C1 reproduced by pickup headPU1.

FIG. 17 also shows means for operating the tape 10 in an intermittentmanner. The operating means includes stop control S of motor MT. MotorMT is energized by the pulse output of the article detector PHC and stopcontrol S is energized when a reproduction head PU1 reads the frameposition indicating pulse previously picked up by head PU1 at a timesuch that the entire picture signal generated by camera CAM has beenrecorded on the tape.

In FIG. 17, the magnetic recording member may comprise either a closedloop tape of such a length to permit the recording of single frame videopicture signals or a recording disc preferably provided with means foreither automatically or manually effecting the change of a picturesignal recording. A continuously rotated magnetic recording drum or discmay also be employed. The output of the signal analyzer 30 extends to acomputer CO for analyzing, recording or operating on the results whichmay be in digital form by means hereinabove described. The computer COis operatively connected to the multicircuit controller or timer 32 forchanging the program thereof to effect changes in the degree of motionof the fixture clamping means operated by servos 58M, 59M and 60M toaccommodate different articles.

The cycle controller 32 may also have additional output control circuitsfor positionally controlling or moving the scanning camera CAM in apredetermined sequence or path to effect a predetermined scanningfunction. Alternatively, the computer CO may be utilized to control themovement of both the article and scanning camera in a predeterminedmanner in which feedback signals are generated to accurately positioneither or both so that an accurate base may be established for thegeneration of picture signals which may be automatically analyzed withpicture signals generated in a similar and predetermined movement of astandard article and the scanner.

FIG. 18 illustrates a recording and control arrangement applicable tothe apparatus of FIGS. 16 and 17. A plurality of different standardpicture signals are recorded and are selectively reproduced forcomparison with picture signals generated in scanning different articleswhich are related to respective of the picture signal recordings onrecording member 10.

Preceding each picture signal is a respective pulse train PC' recordedon track C1. Pulse train PC' is in the form of a binary code. The binarycode is reproduced by reproduction transducer PU1 and passed to a shiftregister 35 which converts the code to a parallel binary code on outputs35'. This code is passed to a code matching relay 36 of the typeillustrated in FIG. 10 having parallel inputs 36' from a computer orcontroller 37.

The output of relay 36 is passed to the trigger control TC whichtriggers a single deflection cycle for the read beam of the scanner CAMonly when the code reproduced from channel C1 matches the input codegenerated by controller 37. Thus, the controller or code setup means 37may be operative in response to means for detecting and identifying theparticular article which article may be one of a plurality of differentarticles moving on the conveyor. Consequently, it may generate aparticular code associated with said article for effecting thereproduction of that picture signal recorded on recording member 10 andthe gating signals provided therewith and associated with the particulararticle. Alternatively, it may be utilized to effect the recording ofthe picture signal generated in scanning the article adjacent or in apredetermined position on the recording member relative to theassociated previously recorded standard picture signal.

The output 36a of code matching relay 36 is passed to the scanningtrigger input TC of the scanner CAM and through a delay relay 36D to theretract control R of the product positioning or clamping servo. Releaseand transfer of the product is thereby accomplished after scanning hasbeen effected and after said servo has been energized to advance againstor otherwise retain the product by activation of the limit switch orphotoelectric detector PHC.

FIG. 18 also shows a connection of the output of stage PHC with meansfor starting the stop control S of the servo MCV for stopping the inflowconveyor 50. Consequently, the next article thereon will not bedelivered to the inspection station or turntable 54 until scanning ofthe article already thereon has been completed. The output of delayrelay 36D is therefore also passed to the start control F of servo MCVas well as to any other servos operative in removing the article fromthe inspection station so that the cycle may be repeated for the nextarticle. In a preferred form of the invention illustrated in FIG. 18,the magnetic recording member 10 may comprise a disc or drum which isdriven at constant speed whereby scanning is effected whenever a code ascommanded by the input device 37 is reproduced from channel C1.

FIG. 19 illustrates a scanning and detection apparatus having featureshereinabove described and a scanner such as a television camera CAM.Camera CAM is automatically controlled in position to scan eitherdifferent image fields or an image field which is greater in area thanthe optical system of the camera. The camera CAM is mounted on aturntable 47 which is rotated or oscillated in a predetermined manner bymeans of a servo 46. The turntable 47 may be continuously rotated toprovide a continuous 360° scan or oscillated by automatic mechanical orelectrically controlled means to scan at different positions in itsrotation. Such positions may be defined by different changeable displayssuch as meter, chart or scope faces.

Accordingly, the turntable drive motor 46 is controlled by an automaticcontroller or computer CO which may also effect control of the movementof the recording member or tape 10 in the event that a predeterminedcondition exists in the field being scanned and is detected by a signalanalyzing means or comparator 30 of the type hereinabove described orany suitable means for comparing the picture signal generated inscanning the same image field during the previous scan with that of thenext scan.

In FIG. 19, the closed loop recording member 10 continues to operate ateither constant speed or intermittently. Member 10 generates bothpicture signals on the inputs to the comparator 30 until a predeterminedcondition exists in the picture signal derived from the last scanningcycle or in a portion of said picture signals as determined by thegating signals of the type hereinabove described. When such a conditionexists, the closed loop magnetic recording belt 10 which containsrecorded thereon picture signals derived from scanning areas defined bythe plurality of different camera positions 47a to 47n is not utilizedfor effecting automatic comparative measurement. A second recordingmeans 41 comprising a magnetic recording disc or drum 42 rotated atconstant speed is utilized for recording both the picture signal derivedfrom scanning the unchanged or previous image field and each subsequentpicture signal generated in scanning the changing image field.Therefore, a running analysis of the changing image situation isobtained.

In other words, the recording disc or drum 42 is operative for recordingjust one picture signal on each of its tracks which may be reproducedthe number of times per minute the recording surface is rotated. Thenumber of rotations is preferably equivalent to the number of cycles perminute which the beam of scanning camera CAM may be driven. The outputof reproduction head PU3 which is generating the standard picture signalis passed to a recording head 44'. Said output is recorded on the firsttrack of magnetic disc or drum 42 and the output of the scanning cameraCAM is recorded through recording head 45 on a second track of disc ordrum 42.

These recorded picture signals are reproduced by respective pickup heads45' and 46' and are passed through a flip-flop switch 34' to thecomparator 30. The flip-flop switch 34' is a double pole-double throwdevice. Switch 34' is automatically switched to pass the reproductionsof the picture signal recordings on rapidly rotating recording member 42to the comparator 30 by a signal generated either on the output of thecomparator 30 by the computing circuit CO or on the output thereof whichenergize an alarm AL in a manner hereinabove described.

Thus, the scanning camera CAM is continuously positioned to scandifferent image fields. Its output picture signal is compared withrespective recordings on the closed loop recording member 10 until apredetermined change occurs in the image field or a portion thereof asdetermined by predetermined variations in the picture signal.Whereafter, the rapidly rotating drum or disc 42 is employed to effectcontinuous comparative recordings which are produced and thereafter thecomparator 30 determines the extent or nature of the changing imageconditions. Accordingly, the output of computer CO or comparator 30 isalso passed to the stop control S of the motor MW which is operative toeither oscillate or rotate the turntable 47 thereby changing thescanning field of the camera.

In a preferred form of the embodiment illustrated in FIG. 19,synchronization between the movement of endless recording member 10 andthe rotation of the scanning camera CAM may be attained by conventionalmeans including use of a single drive for both the tape transport andthe turntable mount for the camera. The drive may be continuous orintermittent and operative such that each time the scanner CAM generatesa picture signal by scanning a particular image field as determined bythe position of turntable 47, a respective comparator signal will bereproduced from member 10 or recording will be effected in apredetermined position on member 10 relative to said comparator signal.The control means 113 of FIG. 20 may also be employed.

FIG. 20 shows means for utilizing a plurality of scanning cameras CAM-1,CAM-2 etc., each of which is adapted to scan a different image fieldsuch as different changing displays, special volumes, etc The mechanismof FIG. 20 is applicable to the apparatus hereinabove described. It isassumed that the field scanned by each of said cameras has a differentoptical characteristic than the fields scanned by the other cameras andthat standard signals are recorded along predetermined lengths of therecording member 10 and are each identified by a respective parallelcode.

A plurality or bank of reproduction heads PUC are adapted to reproducethe picture signal identifying codes from a plurality of recordingtracks. The identifying codes are passed to a shift register 48 whichconverts each code to a series code which is passed simultaneously to aplurality of coded relays 49-1, 49-2, etc. Each of said relays isoperative to generate a control signal upon receipt of the respectivecode which differs from the codes which energize the other relays.

The output of each of the relays 49 is connected to operate the triggercontrol TC of a respective scanning camera. Consequently, only thatcamera will effect a scanning sweep of its image field when a particularcode is present at the reproduction heads PUC. Accordingly, the picturesignal of the camera will be recorded in a predetermined locationrelative to an associated or predetermined picture signal to be comparedtherewith or will be reproduced and immediately compared with apredetermined picture signal which is one of a plurality of such signalsrecorded along different lengths of the recording member 10.

Certain aspects of the scanning, recording and reproduction arrangementsprovided herein may be utilized in improved scanning and detectionsystems. For example, a system may be provided utilizing one or moreslow and/or fast scar video cameras to automatically scan and detectchanges in an image field by comparing the previous picture signalgenerated in scanning a particular image field with the next picturesignal or any subsequent picture signal and automatically determining asdescribed changes therein.

It may be desired to scan an image field such as (a) the face of acathode-ray-tube displaying information which may vary with time, (b) alandscape, (c) or other area such as a warehouse floor, (d) part of aproduction process, etc. and to automatically monitor all or part of theimage field being scanned. Predetermined variations in a particular partof the image field may be used to generate alarm signals, code signals,etc. Said predetermined variations may be discriminated from variationsin other parts of the image field by generating gating signals fromrecordings or other means which pass just those parts of the picturesignal generated in scanning predetermined areas of the image field toanalyzing circuits. As described, the analyzing circuits may be forautomatically noting changes in frequency and/or inflections or changesin amplitude of the picture signal just generated from the previouspicture signal. The variations in the amplitude or inflections may beautomatically analyzed as to degree or amplitude, rate of change,duration, etc. by converting such variables to digital form andanalyzing them by means of a computer. Or the analog portion of thechanged or changing picture signal may be compared with stored analogsignals to determine the nature of the changing image field.

In a preferred system, an endless track erasable recording member suchas a closed loop magnetic tape or drum is continuously driven pastmagnetic recording and reproduction transducers. Any of the arrangementsillustrated in FIGS. 1, 2, 5, 7 or 8 may be utilized for automaticallydetermining variations in the image field being scanned. The scanningcamera may be stationary or may be automatically rotated, oscillated orotherwise positioned to present different portions of the surroundingimage field or environment in its field. A plurality of cameras may beemployed with each adapted to have the signals generated by one or morefield scans thereof gated to the recording transducing means at a timesuch that it may be compared with the picture signal generated inpreviously scanning the same image area or location. In other words, amonitoring system may be provided in which a plurality of differentimages or areas of a single field not accessible to a single scan bycamera may be automatically and continuously monitored.

Referring, for example, to FIG. 3, the standard picture signal or singleframe sweep signal generated in the previous scan of the image field maybe recorded as signal PB1A on track C2 and its location determined byits own vertical frame sync signal or frame locating signal S1 on trackC1. Signal S1, when reproduced, is thus utilized to trigger thedeflection chain of the camera in scanning the same image area which wasscanned to generate picture signal PB1A so as to generate a secondpicture signal which may be recorded as signal PB1B or is immediatelydirectly compared with signal PB1A. The entire picture signal may becompared point-by-point with signal PB1A or just certain portionscompared for any noticeable change or predetermined changes. Theadjustment of the filter or clipping level of video clippers CL-1 andCL-2 and/or the location of gating signals SC11, SC12, etc. may bemanually effected by using manual variable controls or may be computercontrolled or program controlled by conventional servo controlled means.

The picture signal PB1A may remain recorded or may be replaced by thesignal derived from the next scanning. If certain changes occur in thepicture signal, automatic means, controlled by the warning signalgenerated, for example, at the output of clipper CL-1 or AND circuitAN1-2, may be employed to (a) stop movement of the scanner camera andcontinue to scan the image area so changing, (b) retain the camerascanning the changing image area of operative coupling with therecorder, (c) deflection control the beam of the scanner to continue toscan the area which is changing to the temporary exclusion of otherareas, (d) control the optical portion of the electro-optical scanner tobe retained on and magnify the general area of the image field wheresaid change is occurring, (e) bring into operation other scanners of thesame or different characteristics on the area under change such asradar, ultrasonic, infra-red, X-ray, etc. to determine othercharacteristics of the changing phenomena, and (f) sound an alarm.

If it is desired to note when changes of a predetermined character occurin the field under surveillance, a comparator signal of predeterminedcharacteristic, which need not necessarily be a video picture signal,may be generated or recorded, for example, in place of the video picturesignal which is used to compare with portions of the picture signalderived in scanning the field being inspected. For example, it may beknown that a certain condition may exist in a certain portion of theimage field being scanned when the picture signal thereof exhibits apredetermined change in amplitude or frequency along a predeterminedsegment or segments thereof. Then, comparator pulse or analog signalsmay be recorded at predetermined positions relative the frame syncsignal S1. Signal S1 is used to trigger the read beam of the camerascanning the field being inspected. These signals may be compared withand used to gate clipped or filtered portions of the video picturesignal for analysis thereof. Such comparator signals need not berecorded as described, but may be generated in synchronized relation tothe generation of the inspection picture signal by other known signalgenerating means.

In another form of the invention, means for digitizing or analyzing animage field is provided in which portions of the field such as discreteareas differing in shade, color or intensity from other portions orareas not defined by sharp image contrast may be present. It may bedesirable to analyze said portions as to such variables as (a) existenceor coordinate location of an area or areas of a particular intensity,shade or color, (b) determination of the area of a particular intensityor color in the field, (c) comparison of the location degree or coverageof areas of different color intensity or areas lacking discrete or sharpoutline in a first image field with similarly colored or shaded areas ofa second field, etc.

To effect such determinations, the apparatus hereinabove described maybe modified by passing the beam generated and modulated picture signal,which picture signal is generated in scanning the image field beinganalyzed, to analyzing circuitry. The analyzing circuitry includes aplurality of means for filtering and/or clipping different portions ofthe picture signal exhibiting different characteristics. Colorseparation and determination by utilizing either a color televisioncamera to generate a composite color television signal which may belater separated into its color components or combinations thereof byemploying the proper electrical filter means or by employing thenecessary optical filter or filters on the lens of the scanner camera.

A plurality of electronic filters may be employed to separate differentportions of the picture signal of predetermined colors. Then, the outputof each filter circuit or combinations thereof may be used as the hereindescribed gating signals for operating or gating binary digital codesignals generated by a digital clock circuit. The digital clock signalsmay be utilized to determine the location of areas in the image field ofa particular color or shade and/or the shape or degree of coverage ofsaid area or areas of said particular color or colors.

An image field such as a photograph, map or other field formation may bemade up of different areas of different shades of a particular colorsuch as shades of grey, halftone areas, etc. Said shades are scannableto generate a picture signal which varies in amplitude in accordancewith the intensity or degree of the shade being scanned. A plurality ofclipping devices such as clippers CL1 and CL2 shown in FIGS. 3, 4, 4a,4b, 7, 8 and 9 may each be connected to receive the same picture signalbut with each adjusted or provided with a clipping level which isdifferent from the clipping level of the others. Thus, for a particularshade or intensity being scanned, one or more of the clippers may clipand generate an output signal while one or more may not provide anoutput signal.

The outputs of each clipping circuit may be connected to logicalswitching circuits such as illustrated in FIG. 4 to determine thescanning of a particular shade image intensity or color by means of afurther signal or signals generated on further circuits. Each of theclipping circuits may be connected to operate a respective codegenerator when its output is energized or to pass the digital codeoutput of a clock when its output is energized. If each code generatoris generating a different code or codes of signals of differentfrequency, then indications in code form may be derived of thecharacteristics of the area or areas of different or predeterminedcolor, shade or intensity. Such codes may be recorded or immediatelyanalyzed to determine the existence of said areas, location, extent,shape, etc.

The video camera CAM may comprise a conventional television camera or aflying spot scanner. Such a camera CAM is employed throughout thedisclosure to scan and generate video signals representative of theimage or images in the scanning field being inspected. The flying spotscanner may employ a deflection controlled read beam or a solid stateimage sensor containing a suitable number of light sensitive elements.The light sensitive elements generate a suitable video signal when lightis received from the surface of the object being scanned or when theimage field is focused thereon.

One form of a suitable video camera which does not employ deflectioncontrol beam is described in Bell Telephone Laboratories note No.19.3-22, dated March 1972. Light of the image field to be analyzed isfocused onto a solid state area imaging device. The imaging device suchas a silicon chip contains an array of light sensitive storage cellsdefining a charge coupled storage area wherein each of the cells thereofgenerates a stored charge which is proportionate to the incident lightdirected thereon. The integrated frame signal generated by all the lightsensitive cells is then transferred to a storage area and read through aserial register to an output electrode as an analog video picturesignal.

Single frame video picture signals may be generated for the purposesdefined herein by controllably operating the shutter of such a camera.The camera shutter is predeterminedly opened when the object or image tobe inspected is in the field of the camera optical system, such as inresponse to the described article detection means. The shutter is closedimmediately thereafter until the next object or image is in the fieldand ready for the next scanning cycle.

Having thus set forth and disclosed the nature of this invention, whatis claimed is:
 1. A method for analyzing electro-optically scannableinformation using information in a memory, said method comprising:(a)scanning an image field containing variable image information with aradiation beam, (b) detecting optical variations in said image fieldwith an electro-optical detection means, (c) generating electricaldetection signals relating to said radiation beam scanning on the outputof said detection means, (d) comparing said electrical detection signalswith information obtained from recordings in a memory, and (e)generating a control signal when an operable match is effected betweenselect of said electrical detection signals and the information recordedin said memory.
 2. A method in accordance with claim 1 whereinsaidscanning step includes controlling said radiation beam to cause it toscan a plurality of paths in said image field.
 3. A method in accordancewith claim 2 whereinsaid beam is caused to intersect an object duringits scanning movement along at least one of said paths, and said controlsignal is generated from the detection signals generated as a result ofscanning said radiation beam across a portion of the surface of saidobject.
 4. A method for scanning and generating image information, saidmethod comprising:(a) generating a radiation beam, (b) controllablymoving said radiation beam to cause said beam to scan an image fieldcontaining variable optically scannable information along a plurality ofscanning paths whereby radiation of said beam is variably reflectedduring at least part of its scanning movement along a number of saidscanning paths, (c) electro-optically detecting variations in thereflected energy of said beam as it scans said image field andgenerating electrical detection signals which are modulated inaccordance with variations in the reflectivity of those portions of saidimage field defined by said variable optically scannable informationscanned by said beam in its travel along said scanning paths, (d)electronically processing said electrical detection signals andgenerating electrical control signals, (e) computer analyzing saidelectrical control signals and generating coded electrical signalsdefining at least one variable detected during scanning movement of saidbeam along at least one of said scanning paths, and (f) employing saidcoded electrical signals to control the operation of an intelligibleindicating means to cause it to indicate the informationelectro-optically detected by the scanning movement of said beam throughsaid image field.
 5. A method in accordance with claim 4 whereinsaidradiation beam is controllably deflected and caused to scan twospaced-apart portions of said image field, and said coded electricalsignals define information relating to a portion of the image fieldscanned by said beam during its scanning movement along one of saidplurality of scanning paths.
 6. A method in accordance with claim 4whereinsaid radiation beam is controllably deflected and caused toline-scan two portions of said image field containing variable imageinformation, and coded electrical signals are generated from thedetection signals generated by electro-optically detecting variations inthe reflected radiant energy during the scanning movement of said beamalong a plurality of said scanning paths.
 7. A method in accordance withclaim 4 whereinsaid radiation beam is caused to line-scan during itsmovement along at least one of its scanning paths across portions ofsaid image field thereby causing variations in the reflections of theradiation of said beam which is electro-optically detected, saidvariations being detected during said electronic processing steps, andsaid detection signals produce said coded electrical signals during thecomputer analyzing and generating step.
 8. A method in accordance withclaim 4 whereinsaid coded electrical signals are indicative of aplurality of variations in the reflected energy of said beam generatedas it scans at least one of said scanning paths across said image field.9. A method in accordance with claim 4 whereinsaid electrical controlsignals are generated as said radiation beam scans said image fieldalong a plurality of said scanning paths.
 10. A method for scanning andgenerating image information, said method comprising:(a) generating aradiation beam, (b) controllably moving said radiation beam to causesaid beam to scan an image field containing variable optically scannableinformation along a plurality of scanning paths whereby radiation ofsaid beam produces variably reflected energy from the image field duringat least part of its scanning movement along a number of said scanningpaths, (c) electro-optically detecting variations in the reflectedenergy of said beam as it scans said image field and generatingelectrical detection signals which are modulated in accordance withvariations in the reflectivity of those portions of said image fielddefined by said variable optically scannable information scanned by saidbeam in its travel along said different scanning paths, (d)electronically processing said electrical detection signals andgenerating electrical control signals, (e) comparing said electricalcontrol signals with digital information defined by recordings in amemory, and (f) generating a coded electrical signal when an operablecomparative match occurs between said electrical control signals andsaid digital information.
 11. A method in accordance with claim 10whereinsaid radiation beam is controllably deflected to cause it to scansaid plurality of scanning paths.
 12. A method in accordance with claim10 whereinsaid radiation beam is controllably moved to scan a pluralityof paths which are angulated with respect to each other.
 13. A method inaccordance with claim 10 whereinsaid radiation beam is caused to scanback and forth in its travel along said scanning paths.
 14. A method inaccordance with claim 10 whereinsaid electronically processing stepincludes digitizing said electrical detection signals.
 15. A method inaccordance with claim 10 which includesemploying said coded electricalsignals to intelligibly indicate quantitative information relating to atleast part of the optically scannable information scanned by saidradiation beam.
 16. A method in accordance with claim 10 whereinsaidradiation beam is caused to scan a plurality of images in said fieldwhich images sharply contrast in light reflectivity with the lightreflectivity of the background surrounding said images and to therebygenerate sharp inflection in said electrical detection signals.
 17. Amethod for scanning and generating image information, said methodcomprising:(a) generating a radiation beam, (b) controllably moving saidradiation beam to cause said beam to scan a field containing variableoptically scannable information wherein said beam scans along aplurality of scanning paths and whereby radiation of said beam producesvariably reflected energy from the field during at least part of itsscanning movement along a number of said scanning paths, (c)electro-optically detecting variations in the reflected energy of saidbeam as it scans said image field and generating electrical detectionsignals which are modulated in accordance with variations in thereflectivity of those portions of said image field defined by saidvariable optically scannable information scanned by said beam in itstravel along said different scanning paths, (d) electronicallyprocessing said electrical detection signals and generating digitalelectrical control signals, (e) comparing said digital electricalcontrol signals with digital information defined by recordings in amemory, and (f) generating a coded electrical signal when an operablecomparative match occurs between said digital electrical control signalsand said digital information.
 18. A method in accordance with claim 10wherein said radiation beam is controllably moved to scan a plurality ofpaths which are parallel with respect to each other.